Water FIlters

The pre-filters (sediment and carbon) do not normally remove TDS (Total Dissolved Solid[s]). They are there for the removal of particulate and chemical matter such as rust, sand, chlorine, etc. This applies to all micron sizes, even if you use/are using a 0.5 micron pre-filter.

TDS is removed by one of the following:
Reverse Osmosis (RO), De-ionization (DI) or Distillation. Normally, the RO and DI are combined for a complete removal system. The RO process cannot remove all of the TDS on its own. The DI process and distillation can. The DI lifespan depends on what the TDS feeding it is like. This is why the RO process is recommended before a DI filter.

The DI is done by mixing anion and cation resins for ion removal. Distillation is the process of removing water vapors from TDS.

The RO and/or RODI process is more efficient, economical and easier to use than any other process of water filtration.

I want to take a moment to discuss a very basic and important reverse osmosis topic; Pre-filters.

- Sediment filters are designed to remove dirt and large particles from the water. They tend to look dirtier than the other filters; even when first used. This is normal and nothing to worry about.

- Carbon filters are designed to remove chemicals mixed with the water as well as removing sediment.

The optimal situation is to progressively remove the dirt/sediment. This helps distribute the work load and prevents excessive pressure drops. We do this so the first filter protects the next and so on. This helps improve the filter life and improves the overall performance of the system.

Our normal pre-filter array is as follows:

Stage 1 - A ten micron sediment filterStage
2 - A five micron coconut carbon blockStage
3 - A one micron coconut carbon block

Smaller micron rated filters can remove more, but will clog faster. This is why we don't normally use them.

The manufacturer of the FilmTec reverse osmosis membrane requires the removal of oxidants/chlorine and of particles/sediment larger than five (5) micron to comply with its three year warranty. (www.filmtec.com)

As mentioned before, the sediment and carbon filters are only there to remove particulate and chemical matter before it reaches and fouls the RO membrane. There are a few different kinds of carbon - Carbon block, GAC (Granular Activated Carbon), catalytic and PAC (Powder Activated Carbon). We normally use two carbon block filters for their superior chlorine removal and its ability to remove some chloramine. The catalytic carbon is used mainly for chloramine removal.

The RO membrane is there for removal of bacteria, viruses, pathogens, endotoxins, metals, salts and other TDS. Keep in mind that this process still leaves some TDS, but it's within safe levels.

The DI is normally used as a post filter for the membrane. It removes the remaining TDS by the ion exchange process using anion and cation resin beds. Its main function is to remove the rest of the salt and metal ions from the water.

For drinking water units, a "Taste and Odor" filter is installed after the RO membrane. This does not remove any TDS, but it cleans up any taste or odor that may be left after the RO process.

CAUTION!! - Before installing new filters, make sure that the water supply is turned off and the pressure has been released from the unit. This can be done by opening a pure water output line.

Vertical Filters:

(Mainly the pre-filters unless on a smaller unit):

Unscrew the filter housings. Remove old filters from the unit. Install the new filters, making sure they're in the right order:

Stage 1 - 10 micron sediment

Stage 2 - 5 micron carbon block (normally)

Stage 3 - 1 micron carbon block.

Stage 5 - After the RO membrane and only if you have a vertical DI.

Make sure to hand tighten the housings after installation. Too much tightening can lead to the housings cracking.

In-line Filters:

The in-line filters normally have push-in fittings. Simply remove the tubing and/or fittings from the filter. Remove the blue dust caps from your new filters. Then install the new filters making sure of the direction of flow.

In-line filters can be used as pre-filters on smaller units, though they're mainly used as post-filters. The standard in-line filter is 5 microns. If you have a unit with the in-line filters as your pre-filters, the setup is as follows:

Stage 1 - In-line carbon

Stage 2 - In-line sediment

The reason for this is the in-line carbon tends to release grains of carbon which can clog the RO membrane. The sediment follows after it to prevent this from happening.

RO Membrane:

Remove the old membrane by using either a pair of pliers or a screwdriver to put through the holes in the plastic center of the membrane. Make sure that the new membrane has its O-rings well lubricated. Install the new membrane with the O-rings in the housing first.

These are basic instructions for standard filters and may not apply to all units.


The major difference, besides how much water they can make, is the rejection rate. Normally, the lower the GPD volume, the higher the removal rate is.

The 50 GPD membrane has a 97% rejection rate whereas FilmTec redesigned their 75 GPD membranes and it now has a 99% rejection rate. Along with redesigning the 75 GPD, they redesigned the 100 GPD to where it now has a 98% rejection rate. The 150 GPD membrane allows for high volume without a big drop in the rejection rate. It has about a 97% - 99% rejection rate.

The RO membrane, though somewhat fragile, is pretty tough. You can handle it without any problem! We at Air, Water & Ice prefer to use FilmTec membranes over any other.

FilmTec membranes can process seawater, brackish water or tap water (from either a city or well source). This is done by utilizing the thin film composite (TFC) material.

The TFC material is great for removing TDS, but can be damaged by chlorine or other oxidants. This is why pre-filters and pre-treatment of the water is important.

How do you tell them apart? SIMPLE! Each membrane has an alphanumeric ID number. The first two letters indicate what type of membrane is used:

SW- Seawater - TDS removal of 32,000 to 40,000 PPM. These membranes are made with a thick fiberglass shell and operates under 700 - 1,000 PSI (800 is the normal pressure used for seawater).

BW - Brackish water - TDS removal of 2,000 PPM to just below SW membranes. These membranes also have a fiberglass shell, but it's thinner than the SW membranes. The BW membranes work with 200 - 600 PSI.

TW - Taped wrapped - This is normally referred to as tap water membrane. TDS removal of below 100 to 2,000 PPM. Since these are taped wrapped, the operate under low pressures between 40 - 200 PSI.

The next two digits (normally the number 30) is the chemistry element. The following numbers are the size of the membrane. For SW and BW membranes, there are no more numbers are the size. For the TW membranes, these are extra numbers to tell you the GPD (gallons per day) rating of the membrane.


SW30-4040 = Seawater (30) - 4.0" x 40" (4040)

TW30-1812-100 = Taped wrapped (30) - 1.8" x 12" (1812) - 100 (GPD)

How can a 1.8" diameter membrane fit and seal in a 2" diameter housing? The Brine Seal. It's a rubber piece that's wrapped to the TW membranes to form a seal. Since the length of the membranes stays the same, you don't need to go with a different membrane, even if the diameter is slightly smaller.

Are all membranes the same standard size?

As with pre-filters, the answer is no. Different companies can use membranes that are specially made for their unit. For instance, the Evolution 1000 uses a TW membrane that is 17" long. Just make sure you know the dimensions of the membrane before ordering a new one.

For more information please visit www.filmtec.com.

As mentioned before, the RO water has a direct impact on the life on the DI. For calculations, please view the DI resin page on this FAQ.

It also has an impact on a final filter's (aka - in-line carbon) lifespan. Since carbon filters are there normally to treat things like sediment and chlorine, the final filter has a good lifespan to begin with. And because RO water is free of those things, the final filter can last for at least 1-2 years.

This holds true to any other post filter. Since the RO water is already very clean, post filters have a better lifespan than if you were to put them as stand alone filters or have no pre-filtration.

Disolved Gases such as AMMONIA (NH3) will NOT normally be rejected by an RO membrane.

When NH3 is in a environment where the temperature is LESS than 104 Degrees F and the PH is LESS than 7, then more than 95% of the NH3 will convert to NH4 and the membrane's rejection should be better than 98%.

However, if both parameters are allowed to increase, the amount of ammonia will also increase, accompanied by a corresponding decrease in rejection by the RO membrane.

NITRATE ion rejection is dependent on a combination of factors: PH, flux, ionic strength, counterion mix, and membrane type. Tyically nitrate rejection by the RO membrane ranges from 85% to 98%.

All RO membranes are subject to three things; your water quality, water pressure and water temperature.

The membrane is rated at 77 degrees and 50 PSI.

For every pound of pressure lower than 50(PSI) subtract 2% of the output. For every degree(F) below 77, subtract 1.4%.

Example 1: Let's take 40 PSI water at the 77 degree temperature with a 50 GPD membrane.

50 GPD - 20% (40 PSI) = 40 GPD.

Example 2. Now let's take the 50 PSI, but reduce the temperature to about 40 degrees:

50 GPD - 51.8% (since it's 37 degrees colder x 1.4) = about 26 GPD

Note that the typical waste water ratio is about 3 to one in a 77 degree and 50 PSI environment. So in a 50 GPD membrane you will waste 150 gallons of water to make 50 gallons of water. Lower tempurature and PSI will INCREASE the waste water, So in the above examples the total water will remain at about 200 gallons so the waste water will be 160 in example 1 and about 174 in example 2.

These are all estimates but you get the idea.

Are Dow Filmtec reverse osmosis membranes and ion exchange resins effective at removing silica from water?

Dissolved (reactive) silica

Silica (SiO2) exists in water in equilibrium with the bisilicate (HSiO3-) ion as a very weak acid. In the ionic weak acid form, silica can be removed by strong base anion exchange resins operated in the hydroxide cycle, such as DOWEX MARATHON 11. Since the two forms of silica exist in equilibrium, silica can be almost completely removed from solution, reaching part-per-billion levels in many applications. When present as a single unit of silica, in equilibrium with bisilicate, the compound is termed reactive silica.

Colloidal silica

Silica can also exist as a polymer, often referred to as colloidal silica. These long chains of individual silica units exhibit virtually no charged ionic character, and cannot be removed by the ionic process of ion exchange. Membrane treatment such as FILMTECTM reverse osmosis membranes and DOW Ultrafiltration Modules can remove colloidal silica. Reverse osmosis offers the additional advantage of significant reduction (98%+) of reactive silica as well.

A reverse osmosis membrane is a very tightly wrapped microfiber that has a .001 micron rating. Water is forced through the membrane by water pressure. Only the purest water molecule can penetrate the membrane.

There are two kinds of water coming out of the membranes: the pure and the waste water. The pure water is also called the permeate, product or dilute solution. The waste water is also know as the brine or concentrate.

The pure water has low TDS. The waste water, however, is normally higher in TDS than your tap water. This is because of the pre-treatment of water before the RO membrane.

Reefkeeping - Typhoon Information

All of all reefkeeper units make the same quality water. The difference in Typhoon, Typhoon III & Extreme Typhoon III? FEATURES!!

They all have the same filters, membrane and DI (to a degree). They all produce zero TDS water.

The difference is in the features.

The Typhoon is a great basic unit. It comes with a built-in fast flush valve. Outside of this, there isn't any other feature. This is all you really need.

The Typhoon III has an RO only valve, which allows you to get water, before it goes through the DI. This is good for filling up bottles of water of drinking water and for testing the water coming out of the membrane. It also has a DI bypass valve, and a fast flush valve, which help to extend the life the DI and membrane. The Typhoon III also comes with a hand-held TDS meter. The TDS meter is used to measure the total dissolved solids.

The Extreme Typhoon III has all of the same features the Typhoon III , but also includes a 150 GPD membrane, built in PSI gauge, a built-in dual TDS meter, a TDS alarm, a float valve and the upgraded Catalytic Carbon (GAC) filter for removing chloramines/chlorine. (Replaces the 5 micron carbon block).

When you get a new unit, you should flush off or run about 3 gallons of water through the system. This is to remove any carbon fines and preservatives off of the RO membrane.

If you have the fast flush and/or DI Bypass valves, open them for the flush. On a new unit, remember to flush for 3 gallons or one hour (which ever comes first/easiest is fine).

After installing new filters (excluding the RO membrane), a good 5-15 minute flush is fine. If you install a new membrane, a good 30 minute flush is needed.

On all of these units (with the exceptions of the Hurricane Dual Home Reef, Max 50 and the Mighty Mite with DI) is the ASOV (automatic shut off valve). It's activated whenever there is back-pressure on the output line. If there's no back-pressure, it lets the water run. If there is back-pressure, it shuts it off.

All you need for this is either a ball valve for manual shut off or a float valve for a completely automated shut off system.

On the Hurricane and Max 50, the ASOV has been replaced by the permeate pump. The Mighty Mite with DI has no shut off switch because you normally shut it off at the source, not the product (pure) water.

The Typhoon models are more for aquariums with higher volume needs. They come with standard filters and a vertical DI* (6,800 grains capacity).

The Compact reefkeeper models are more for aquariums with lower volume needs (100 and below gallon tanks). These can be used for larger aquariums (especially if space is an issue), but the DI might exhaust faster. This is because the use the in-line DI* (3,400 grains capacity).

The Dual Home Reef models are a good step if you have both aquarium needs as well as a need for drinking water. While the old and new style models use the in-line DI filters*, the Hurricane model uses a vertical DI*.

As with most DI units, a trash can or other open-storage tank is used for the DI water. With the Dual Home Reef units, a pressurized storage tank is included for the drinking water, but the DI line is separate from it. Though you can use the pressure tank for the DI storage, the high flow coming out of a pressure tank will cause a DI to exhaust faster.

For calculations on how long a DI will last, please look at the FAQ for the DI filters.

The 75 GPD membrane is usually the preferred membrane to use. It has a good rejection rate (about 99% [stabilized]) and makes up to 3 gallons/hour.

The 100 GPD membrane has been redesgned with a higher rejection rate (about 98% [stabilized]).

The 150 GPD membrane has a good rejection rate (about 97% [stabilized]) and allows for high flow. Though this membrane has this special feature, it's not recommended to use unless you have high volume needs.

As mentioned before in our filters, membranes and DI FAQ pages, the filters need to be replaced when:

Pre-filters should be replaced at least annually. This includes the 10 Micron Sediment filter, the 5 Micron Carbon block or Catalytic Carbon filter and the 1 Micron Carbon filter (if one is installed.)

The sediment filter does tend to look like it's getting dirtier faster then others. This is normal. Since it's the first filter, it's removing most of the heavy particulate matter. If water production slows, see it if's the sediment filter first.

The RO membrane needs to be replaced every 3-5 years. If your water is hard and you do not have a softener, then you may need a larger fast flush flow restrictor. This is just a temporary measure and will only slow down the scaling process. *

The DI is based upon how well the RO removes TDS from the water. *** Though we recommend replacing it annually, it may need to be changed more or less often. Go by TDS readings instead. If the TDS is above 5 PPM {stabilized}, then you should replace the DI.

* See www.filmtec.com for warranty details

* See our DI FAQ page for calculations

Fittings - ASOV - Check Valve

Reverse Osmosis systems must make drain water to operate.

The automatic shut off valve (ASOV)'s purpose is for automatically stopping the drain water.

The ASOV is designed to work under 40-75 psi incoming pressure.  

The ASOV will stop the flow of water BEFORE the membrane when the water pressure directly AFTER the membrane is approximately 85% of the water pressure directly BEFORE the membrane, thus shutting your system down.

The ASOV has TWO sides with "runs" of tubing going directly through the ASOV.

Side 1:  The side with the screws:  This side is for the RO (pure) water.  The tubing

runs across the top of the valve (the side with the screw heads). ( The RO water can run either right or left through the ASOV, it does not matter right or left.  Then the filtered supply water runs  across the bottom of the valve in the direction indicated.  When the pressure on the pure water side of the system builds up to 60% of your home water pressure a small piston is pushed down and closes off the supply water.  So when the RO tank is full the pressure builds up into the unit. That back pressure causes the piston to close and no water enters the system. The entire unit shuts down shortly.

It is the only real moving part on the system. You need to see if the screws on top of valve can be snugged up, if that does not cure any of the noise we will send a new ASOV right out. System shuts off when the pressure tank is full or the line from the reef line is shut off. Sometimes it takes several minutes for the ASOV to completely shut down. If this unit also is attached to a float valve storage tank, evaporation from the tank will the ASOV to occassionally come on and off to refill the evaporation.

If your unit is not shutting off when the tank is full ... the asov maybe stuck ... thump the asov WHILE MAKING WATER!

Sometimes the ASOV will vibrate and be noisy ... this is common in new units or after filter changes .... This vibration is "air" stuck in the unit, after a few days this air will be absorbed and the sound will go away. You can get rid of this vibration quickly by turning the entire unit on its right side then its left side several times WHILE MAKING WATER. This allows the air to escape!

Our units have a check valve installed on the pure water line, at the membrane housings pure water outlet. It is built into the elbow fitting. If that valve does not work than the system will not function correctly. The ASOV will not shut the water off. Should it fail, the normal failure mode for this valve is to stick shut, not to stay open.

In the rare event the check valve should fail, or your RO unit from another manufacturer did not come with a check valve, we can supply an in-line check valve so you will not have to disassemble the unit. Simply insert the check valve on the pure water line.

To install:

The flow restrictor needs to be installed on the drain line. Just cut the tubing squarely and push in the new restrictor.

To replace:

You will have to locate the old flow restrictor. There are two kinds used: hooked on the outside of the tubing {newer style} and inside the tubing {older style}

Older style restrictors - they're usually in the tubing closer to the fittings of the membrane housing. If not, they're somewhere in the line before the tubing runs off the RO unit's bracket. Remove them by either pulling them out of the tubing or cut off the section of tubing they are in. Install the new one.

New style restrictors - Just simply remove the old and install the new one. Newer restrictors may be push in (like the ones we use) or have Jaco nut fittings (which are just screwed on.)

Fast flush - When to use:

The flushing process needs to be used whenever you first get an RO unit, let it sit inactive for more than 1 day or when you replace the filters and membrane. When you first get an RO system, it's good to flush it off for at least 30 minutes. You have to flush off the unit for 1 minute per day of inactivity (i.e. - if your unit sits inactive for 5 days, flush it off for 5 minutes.) When you change the filters, a good flush of about 15 minutes is a good idea.

Cylindrical cartridge labeled 'Flow' with an arrow and a number is the flow restrictor. The flow restrictor regulates the water flow in the system. All reverse osmosis systems must rinse. If the ability to rinse is comprised expect the system to stop producing pure water.

The new flow restrictors we sell are combined with a flush valve. When the valve is closed (perpendicular), it acts as the flow restrictor. When opened (parallel), it acts as a flush. Please note that the valve does NOT shut off the drain water.

Looks very complex, but is really very simple. The water is simply traveling across the valve from left to right or right to left depends on how you look at it. Pure water travels across the top of the unit, the filtered water across the bottom. The valve has a top and a bottom. The top is the side with the four screws visible. The bottom has no visible screws and is marked in and out. The bottom of the valve is connected between the pre-filters and the membrane. Water from the pre-filters is directed to the ASOV "in". The filtered water continues from the "out" of the ASOV to the membrane end with only one connection, the membrane water inlet. So the bottom of this valve goes in between the filters and the membrane. The top side with the four screws connects across the pure water line, from the membrane pure water outlet.

The pure water outlet of the membrane is on the membrane housing end with two connections. One connection goes to the drain water and the other is the pure water. The drain connection is not the one you want. Once you have located the pure water line, cut it off and install the ASOV. Now the pure water path is interrupted by the ASOV as well.

An ASOV (automatic shut off valve) is a must! It saves water, extends the filter life and improves the performance of your unit.

As the storage tank fills the pressure inside increases, when the pressure equals 1/2 to 2/3 your feed water pressure, the water to the system is shut off. No waste. Since you subtract the storage pressure from the operating pressure, the storage pressure needs to be limited.

The automatic shut-off valve. This valve allows your system to turn your system to turn off the water supply, using pressure from the pure water side of the system. Then the ASOV will turn off the water supply to the unit, whenever there is sufficent pressure on the pure water side of your system.

Installation Questions

The optimal installation has the shortest distance between system components. Long runs of tubing produce pressure loss due to tubing resistance.

You can increase the distance between components of your water system but you will loose some water pressure & production. Pressure lost in long tubing runs reduces overall system performance. If you have a long distance to go between components or connection points, please consider using 3/8 tubing instead of the 1/4 inch tubing provided . We stock 3/8 tubing . What about going up stairs from the basement? You lose one pound of water pressure for every 2.3 ft. you run tubing uphill.

When installing a drinking water system with a pressurized storage tank:

The best results come from installing the tank on the same level as your most common usage. (You can install the tank downstairs, but you will lose some delivery pressure.)

You can install the tank in the rafters of the basement, The tank may lay down, or stand up no difference in performance. etc.  

Placing the R.O. system in the basement is OK.  Install it at eye level. Some customers build a shelf and secure the unit to the basement wall.

The important thing is the distance from the system to the sink Gooseneck faucet .

 Final filter on drinking water units:

The optimal install is with the removal and placement of final filter so the water does not have to go back down to the final filter after the tank.

You will need some additional fittings for this call or e-mail.

Drain line: Can run up, but again you will loose some pressure.


If you have to run tubing over 10 ft. (drain vs. product water) it is best to choose the waste water connection as the long run.

*The further you run tubing across any distance the greater the pressure loss due to tubing resistance.

(Maximum recommended run 50 ft.)

When running tubing up (i.e. basement to kitchen) you encounter losses due to gravity and tubing resistance.

* For any tubing run over 10 ft. we recommend using 3/8 inch tubing

It would be best to use the standard supply valve on the cold water supply tube going to the faucet. it will operate automatically and you will never know they are there. The others are temporary set ups. Usually the hose and faucet adaptors are used with reefkeeping systems that do not come with the storage tank are not used every day as drinking water systems.

The membrane vessel has a cap at one end and a connection.  Remove the tube turn the cap to the left. The cap will come off and the old membrane will be visible.

You can use pliers or some other tool to grab and pull on the plastic membrane product tube. Now you only need to pull for about an inch. After that inch the membrane will fly out if you keep pulling. Take the new membrane out of the bag, lubricate the o-rings at the end with water proof silicone lubricant. If you do not have any silicone, use some dish soap. The dish soap will make the o-rings slippery enough to install them correctly. Insert the membrane into the membrane vessel, make certain that it seats in the connection at the bottom. The membrane should fit just about flush with the end of the vessel, when correctly seated. Replace the cap and reconnect the tube.

Now to the flow restrictor: The other end of the vessel has two connections. One waste the other pure water. Locate the waste water line follow it and see if you have a flow restriction device on it. If you find the device replace it with the new correctly sized flow restrictor. The arrow points to the drain.

If you do not find one it is because the flow restrictor you have in inside of the drain tube. Remove the drain (waste) tube at the membrane housing and inspect it for a funky little piece of tubing and a small cap. Remove this in-line flow restrictor. Reconnect the tube to the membrane housing. Then install the new flow restrictor on the waste water line. Arrow pointing toward drain.

Electric Drill

1/4" Drill bit for Drain saddle and mounting to wall

9/16 inch drill bit for faucet mounting hole

Sharp Utility knife or our tubing cutter for cutting the 1/4 inch tubing. tubing

How to perform a TDS test

1. Start making RO or RODI water (open a pure water line).  All systems have a RO ONLY line, our reefkeeper systems have a RODI line or DI bypass. If you have a drinking water system, we advise you close the blue tank ball valve on the pressure tank and just turn on the RO faucet for this step.  If you have a RODI unit and are lucky enough to have a DI bypass, then you will open the blue ball valve as to open the DI bypass so we don't waste any DI resin (If you do not have a DI bypass on your RODI system, you could still make RODI water or disconnect the tubing going INTO the final DI filter).

2. Fast flush your system for 15 minutes. On ALL of our systems, this simply means to turn the black handle on the flow restrictor to the right 90 degrees so the black handle is pointed TOWARDS the arrow on the flow restrictor (PARALLEL).  HINT> there is only ONE black handle on our units and it can be found easily by looking down from above your system.  

3. Return the black handle on the flow restrictor back to normal operations mode (closed).  Just turn the black handle to the left 90 degrees so it is pointed perpendicular to the tubing and pointed AWAY from the drain lines tubing. NOTE> This process removes the "tds creep" in the lines that do not accurately represent the water quality of the system.

4. Make ONE gallon of RO water. (about 10-15 minutes) .  NOTE> This will remove the remaining "tds creep" in your system that we do not want to pick up in our TDS test.  

5. Get a clean cup and your TDS meter.  Do not use the cap of your TDS meter.  If you need a TDS meter [click here] !

6. Fill your cup with RO water and take a TDS reading of the RO water sample.  NOTE> Stir the tds meter in the cup with the sample so there are no air bubbles around the probes of the tds meter.  Allow 30 seconds to pass before you take note of the number appearing on your TDS meter.  As a side note, if you have water colder than 77 degrees a non temperature adjusted tds meter will show LESS tds ppm than what is actually present. The opposite is true aswell...if your water sample is over 77 degrees, your tds meter's ppm will overstate how much tds is in your sample. (one can adjust about 2% per degree celsius for the correct tds present in a water sample).

7. Repeat step 6 and take a tds reading of your TAP (unflitered) water.  NOTE> Before doing this, empty your cup with the RO water sample and shake out the excess water in the cup and on the TDS meter.  Then go to your sink faucet (or somewhere close) and take your sample.

8. Compare RO tds reading to TAP water tds reading.  Your RO water tds reading should be approximately 5% of the TAP water tds reading. If your TDS reading is more than 10% of your tap water TDS, it's time to replace your membrane [click here for membranes]. EXAMPLE: Your RO tds reading is 10 ppm tds.  Your TAP water tds reading is 200 ppm tds.  This is a 95% rejection rate. [95%=100%-(10ppm/200ppm)].

9. If you have a RODI unit you have a DI resin stage. Now is a great time to take a TDS reading of the RODI water that is leaving the unit. It should be close to ZERO! If this is a new DI filter and your meter reads higher than zero, your TDS meter is WRONG!

FYI: A quick and easy test to determine if your DI is exhausting too quickly is calculated as follows: 3,000 divided by the TDS/PPM of your RO water = Total estimated gallons of ZERO TDS water the resin will process before it starts exhausting.

RODI EXAMPLE: If your tap water TDS is 200 PPM ....  the TDS of your RO water (after the membrane) will have about 5% remaining, so 10 PPM. IF you have a standard 10" refillable DI cartridge, divide 3000 by this 10 PPM and that equals about 300 gallons of RODI water you will make before your DI resin is exhausted. If you have a in-Line DI filter will last only half as long. The 20" refillables will last twice as long. If you do not fast flush your system before you start making water, TDS creep can reduce this volume.

FILMTEC Membranes - Ammonia and Nitrate Rejection

Disolved Gases such as AMMONIA (NH3) will NOT normally be rejected by an RO membrane.

When NH3 is in a environment where the temperature is LESS than 104 Degrees F and the PH is LESS than 7, then more than 95% of the NH3 will convert to NH4 and the membrane's rejection should be better than 98%.

However, if both parameters are allowed to increase, the amount of ammonia will also increase, accompanied by a corresponding decrease in rejection by the RO membrane.

NITRATE ion rejection is dependent on a combination of factors: PH, flux, ionic strength, counterion mix, and membrane type. Tyically nitrate rejection by the RO membrane ranges from 85% to 98%.

How often should I replace my filters?

Pre-filters should be replaced every 6 - 12 months. If you are needing to change filters more often than this we recommend stepping up into a bigger unit! Not sure? Were here to help 772-461-0256.

Pre-filters are before or upstream of the membrane and help protect the membrane from premature bio-fouling caused by primarily chlorine. No pre-filter on the market today is designed to remove TDS (total dissolved solids); again, the purpose of the pre-filters is to protect your RO membrane...which does up to >99% of the work purifying the water.

A properly designed filter array will always allow the membrane to achieve optimal performance through the life of the pre-filters. For this specific reason, NEVER EVER install less than a ONE micron filter in a pre-filter array.

DI Resin - (Deionization)

Yes, a DI cartridge can be used as a stand-alone filter. However, the lifespan will be reduced greatly (unless your water is very low on TDS to begin with). Just refer back to the DI life section of this FAQ.

Normally, a stand-alone DI is used in either lab or car washing applications. Though you can use our DI filters for these applications, we do not normally recommend it. We might refer you to a different company for DI filter units that were made specifically for these applications if we do not think that ours will last long enough for your use.

Typically, you will want the mixed bed resin. However, you can use separate beds (anion and cation) as well.

First of all, there are two kinds of DI filter cartridges; vertical and in-line. Both can filter out the TDS down to zero (or very close to it), but they have different filtering capacities.

To figure how long they'll last is simple math. Take the capacity of the DI filter and divide it by the TDS of the water feeding it. The lower the TDS feeding it, the longer the DI will last. This is why it's good to have a RO membrane to remove most of the TDS before using a DI.

For Example:

The vertical DI has a capacity of 3,000 ppm. The in-line DI has about half that capacity, so around 1,500. Let's say that the RO is reducing the TDS down to 10. This is what the equation will look like for each DI:

Vertical DI:

3,000 (ppm) divided by 10 (ppm) = 300 (gallons of pure [-0- TDS] water)

In-line DI:

1,500 (ppm) divided by 10 (ppm) = 150 (gallons of pure [-0- TDS] water)

There are some exceptions to this equation. Higher than usual levels of some TDS can cause the DI to exhaust faster. It's also important to know when to flush the membrane before starting to make RODI water.

Some examples of elements that, if in high levels, can cause the DI to exhaust faster are: phosphates, nitrates, silicates, salt, calcium, etc. The RO membrane can remove most of it, but the DI would have to work harder than usual to remove it all from the water.

If the unit has sat inactive for more than one day and you do not flush off the membrane before making RODI water, it can cause the DI to exhaust faster as well. Make sure to flush off the membrane for one minute per day of inactivity. This doesn't really apply to those who use their unit every other day or every day. However, if you use it that much, you should still flush the membrane off once a month for about 30 minutes or so.

Instructions on how to flush are in the Fittings FAQ.

This is a simple process. Simply remove the DI cartridge from the housing. On the bottom of the cartridge is a screw-on cap. Unscrew it and remove the foam piece. Dump out the old resin into a garbage can/trash bag. Fill up the cartridge with the new resin and put the foam piece back in place. Screw the cap back on and you're done!

CAUTION!! - Resin is a very round material. Be careful not to get it into your eye. If you do, flush out your eye for about 15-20 minutes. Also, if it gets on a hard floor, be careful not to step on it because it can cause you to slip.

Are Dow Filmtec reverse osmosis membranes and ion exchange resins effective at removing silica from water?

Dissolved (reactive) silica

Silica (SiO2) exists in water in equilibrium with the bisilicate (HSiO3-) ion as a very weak acid. In the ionic weak acid form, silica can be removed by strong base anion exchange resins operated in the hydroxide cycle, such as DOWEX MARATHON 11. Since the two forms of silica exist in equilibrium, silica can be almost completely removed from solution, reaching part-per-billion levels in many applications. When present as a single unit of silica, in equilibrium with bisilicate, the compound is termed reactive silica.

Colloidal silica

Silica can also exist as a polymer, often referred to as colloidal silica. These long chains of individual silica units exhibit virtually no charged ionic character, and cannot be removed by the ionic process of ion exchange. Membrane treatment such as FILMTECTM reverse osmosis membranes and DOW Ultrafiltration Modules can remove colloidal silica. Reverse osmosis offers the additional advantage of significant reduction (98%+) of reactive silica as well.

A water softener is needed if your water is hard. Hardness is able to get through the pre-filters and clog the RO membrane over time. Hard water starts at 4 GPG (grains per gallon) or roughly 68 ppm (hardness).

If you don't know if your water is hard, you can request a water quality report from your city/county. You can also have it tested by someone else. We offer a free testing of your water for TDS, hardness, iron and PH.

You can use a softening pre-filter (cartridge) if your hardness is less than 10 GPG. We offer them both in vertical and in-line cartridges. If you have more than 10 GPG, you will need a whole house softener. We do not deal with whole house softeners anymore. We will be able to let you know where to get one, but cannot recommend one over the other.

No, it's nothing to worry about. As long as there's water flowing through the DI, it doesn't really matter. It's air trapped inside of the housing. If you don't like how it looks, you can unscrew the housing a little to release the air. When the water fills the housing/chamber tighten it down quickly to avoid a small blast of water everywhere.

What happens if it fills back up with air after I do this?

Just repeat the process. It will eventually stop filling with air and leave the chamber full of water most of the time. If not, then it's still okay.

It is the removal of mineral ions by using the ion exchange process. Using a mixed bed of anion and cation resins; ions, salts and minerals can be entirely removed from water.

The RO membrane has a direct impact on the life-span of the DI. The RO membrane can remove about 95-99% of TDS (minerals) in your water. When a DI is used after the RO membrane, you can expect almost 100% removal of the TDS.

Drinking Water Systems

Yes, no problem. This is a simple task. All you need is a couple of "T" or "Y" fittings and maybe a check valve.

Just keep in mind that each individual tank will fill up and release water as needed based upon location of the tank. One can fill up faster than another. This is normal.

No, not really. It's helpful in keeping any strange tastes and odors from coming out of the unit, but isn't essential.

Why pre-install it if it isn't needed?

Everyone's water is different. We cannot determine what it will smell or taste like after the RO membrane. It's better to be safe than to be sorry.

Does adding a carbon filter after the membrane impact TDS?

It may or may not. Sometimes it inserts small amount of TDS back into the water. It doesn't hurt you so you don't have to worry about it. Most of the time, it doesn't do anything other than what it's supposed to.

Pressure tanks are usually either a metal or plastic tank with a food-safe (plastic*) bladder. An air pocket that surrounds the bladder is what pressurizes the tank. This pressure gives you the amount you need to get water out of the faucet and/or the refrigerator.

Without the pressure tank, you can still get water out of the system, but not in good quantities. You can use a delivery pump to boost the pressure coming out of it to maintain good flow, but it's more costly.

Pressure tanks do have an adverse effect on the DI. This will be discussed more in the reefkeeping section related to the Dual Home Reef systems.

The bladder will not leak anything back into the water. This is why it is "food-safe".

You will need a permeate pump if you want to use your RO water for both drinking water from the RO faucet and get water from an icemaker/fridge. The permeate pump increases the pressure in the tank by filling it up more than what a RO membrane can on it's own. This causes higher outgoing pressure which many need in order to hook up their RO system to the fridge.

So, what if I already have really good pressure? Can I go with a basic system?

You can try to hook basic system if this is the case. We normally recommend trying hook-ups without pumps first to see if you actually need one or not. Though these are nice to have because of the extra benefits, they may not be needed.

For more information about this pump, please view our FAQ page on the different kinds of pumps.

A drinking water system is a RO unit with an in-line carbon filter as the post filter to remove any abnormal tastes or odors. It normally comes with a pressurized storage tank and a RO faucet. They reduce the TDS down low enough for safe drinking water levels, but are not completely free of TDS.

Reefkeepers (discussed in the next FAQ) are RODI systems and provide -0- TDS water. Reefkeeping units do not come with any tank or faucet.

Normally, a drinking water unit comes with a 50 GPD membrane. This is good if there is no more than 3-4 people in the house. The 75 GPD membrane is used if you have 5-7 people in the house. The 100 is used for 7+ people in the house. Most people do not need to use the 150 GPD membrane for drinking water. You can, but it's not necessary.

Pumps - UV

Ultra violet light will kill (destroys the DNA) of any organism and destroy the ability of organisms to replicate. They can not reproduce inside of you, so you can not get sick. In this manner they protect you from disease. All US City water has chlorine or chloramines in the water which kills these organisms. UV lights are normally only needed for well water where organisms might be present.

The Power Station water pressure booster system is a quiet,low voltage pump. It comes with a power transformer, a pre filter, a high  pressure switch, excessive water bypass valve and fitting to convert from the 3/8 port to the ¼ inch tubing. Totally ready to go and includes an Allen wrench to adjust the pressure switch.

Homes with average water pressure should not need a booster pump . Average water pressure is (50)psi. Booster pumps increase the feed pressure of the R.O. system. Yes they enhance the overall performance the system.

Why is a permeate pump good for drinking water units?

A Reverse Osmosis drinking water system requires pretty strong water pressure (at least 35 psi) to force water through the R.O. membrane, while flushing the bad elements to the drain. The lower the water pressure, the less "good" water you get and the more "waste" water you produce. The average membrane rating is based on a constant feed water pressure of (50) psi using 77 degree water. The average "real life" application provides much less favorable conditions than this.

The end result is that your R.O. system is drastically under-performing. To make matters worse, the pressure tank that stores your R.O. water compounds this problem. When full, the R.O. tank has an internal pressure of about close to (60)% of your tap water . This pressure is fighting the inlet water pressure. The inlet water pressure is trying to force water through the membrane and into the tank. Even if you have strong water pressure of 60 psi; as the tank gets close to full, the actual pressure on the membrane is only 20 psi.

The permeate pump helps with this problem.

In typical R.O. systems, increased tank pressure causes decreased pressure across the membrane. This decreased pressure causes a substantial decline in system performance and efficiency. A Permeate Pump enhanced R.O. maintains full pressure across its R.O. membrane, even as tank pressure reaches its maximum levels. This reduced back pressure from the storage tank ensures both better water quality (maximum TDS reduction), longer filter life and extended membrane life. In typical R.O. systems, increased tank pressure results in decreased recovery rates. A Permeate Pump enhanced RO system, by automatically minimizing back-pressure, accelerates recovery rates (and reduces tank refill times) by up to 65%.

The permeate pump also reduces waste water:

In typical R.O. systems, several gallons of wasted tap water (discharged to drain) are required to create a single gallon of purified R.O. water. A Permeate Pump enhanced R.O. system, will reduce waste water by up to 80%, helping to conserve an important natural resource while significantly increasing component life. It can be argued that the permeate pump will easily pay for itself saving the wasted expense of changing out filters prematurely and conserving water.

The normal ratio (3-4 gallons of waste per 1 gallon of pure) is based on no back pressure from the tank. Back pressure slows the system down. When you have a nearly full tank, the waste ratio exceeds the norm by quite a bit. The production slows, but the waste remains constant. So the effect is a much higher ratio.

The permeate pump requires no electrical power. It works by taking advantage of the flow of water produced by the waste water to decrease the back-pressure in the line going to the RO storage tank. In short, it nearly draws the water off of the RO membrane into the tank. As a result the pump can increase production by as much as 400% while decreasing waste water by as much as 80%.

The permeate pump only works on units that have pressurized storage tanks. The have no effect on atmospheric tanks. This is because the work with the pressure on both sides. Since an empty tank has no back-pressure, the pump does nothing.

There are three kinds of pumps we use; the booster pump, delivery pump and the permeate pump.

The booster pump does exactly that; boosts pressure going into your system.

The delivery pump also does what it says; delivers water to multiple sources or helps with long distances.

The permeate pump is a useful pump if you have a drinking water system. It is an energy recovery device (ERD).

The booster and delivery pumps can be used on all systems with the right conditions. The permeate pump can be used only on units that have a pressurized storage tank.

The application of an Ultra Violet unit post membrane is purely redundant sterilization. However the application of a UV unit as a pre filter can lead to enhanced performance and longer membrane life.

Why? Bacteria that have had their DNA scrambled cannot replicate inside the system filters or membrane.

Food and energy are available to bacteria in a water system. Especially in systems with clear housings so popular with reefkeepers.

Light provided energy and the sediments and dirt trapped by the filters provide food. Remember all UV systems should only be used on sparkling water, water that has been filtered to five microns. Any sediments or particles in the water larger than five micron can shield bacteria from the UV rays.

Delivery pumps make possible multiple taps and improve performance of long distance connections. Delivery pumps are popular residentially for sending pure water to bathroom sinks or to wet bars. Commercially they can be used to move water all around a fish store , or some other application where water under solid pressure is required.

Terms, Definitions, Abreviations

We will refund the FULL amount of all product purchases made by customers if the product is returned by the customer UNOPENED and UNUSED within 30 days after purchase.  We do not have a restocking fee, but we do not refund any shipping charges and customer must pay to have the items returned to us. If the customer received free shipping with the original purchase, then the amount of the refund will be reduced by the amount of free shipping that the customer would have been charged.


acidity— a characteristic that can make water corrosive and unpleasant; acidity must generally be corrected with neutralization

activated carbon— carbon which has been chemically treated to improve its adsorption properties and filtration capacity

adsorption— the process by which contaminants react with activated carbon and are removed from water

aeration— an oxidation process in which air is injected into water generally to convert an unwanted substance into a solid form that can be filtered


brine— the solution a water softener uses to clean its media bed of captured calcium and magnesium in preparation for service

brine drum— the brine preparation and holding tank on a water softener


calcite— the media used in a neutralization system to neutralize acidic water

carbon filtration— a common water filtration method which uses activated carbon to adsorb contaminants

chlorine— a common water disinfectant used by municipal water utilities

conditioned water— water free of dissolved calcium and magnesium (hardness minerals); also referred to as soft water

countercurrent regeneration — a type of regeneration in which the flow through a water conditioner is reversed during the cleaning process for greater effectiveness and efficiency

cryptosporidium— probably the most common and certainly the most notorious of a group of microorganisms called cysts; "crypto" was responsible for a major waterborne illness outbreak in Milwaukee in 1993

cysts— any of a group of microorganisms that include entamoeba, giardia and cryptosporidium; when ingested, cysts can cause gastrointestinal illness among others and often have more problematic effects on children, the elderly and people with immune deficiencies


demand-initiated regeneration (DIR) — a process in which regeneration is initiated based upon a household’s water use instead of at a preset interval

drinking water— the one percent of a household'’s entire water use that is designated for drinking or food preparation; also referred to as food grade water


ferric iron — dissolved iron which has been oxidized and transformed into an orange particulate

ferrous iron — dissolved clear iron; often found in well water


hard water— water that contains dissolved calcium and magnesium

hardness— the amount of dissolved calcium and magnesium in a water sample, typically measured in grains per gallon (gpg)

hydrogen sulfide— an obnoxious gas with a "rotten egg" odor found in some water


ion exchange— a water softening process in which hardness ions (calcium and magnesium) are exchanged for sodium or potassium ions

iron— a common element that is absorbed by water as it passes through the ground; iron is often found in well water and can cause rusty orange stains on clothing and household fixtures


lead— a tasteless, odorless water contaminant that may be leached from lead-based solder used to join pipes


manganese— iron'’s close cousin commonly found in well water; manganese can cause black stains on clothing and household fixtures


neutralization— the process by which water'’s acidity is adjusted to a neutral range; acidic water can be corrosive

a process in which an oxidizer (commonly air or chlorine) reacts with a dissolved substance to convert it into a solid form that can be filtered


recovery rate— a measure of a reverse osmosis system's efficiency; generally measured as amount of water produced divided by amount of water used; a rate of 25% is usually considered efficient

regeneration— a water conditioner'’s cleaning cycle; the cycle prepares the system'’s resin bed so it can soften water again

resin— tiny beads used by a water conditioner to soften water; the place where ion exchange occurs inside a water conditioner

reverse osmosis— a filtration method in which water is forced through a semi permeable membrane which rejects contaminants


scale— a hard, crusty substance that remains after hard water dries

soap scum— the substance which results from the reaction of the hardness minerals in water with common household soaps; usually evident as a bathtub ring or glass shower door film

soft water— water free of dissolved calcium and magnesium (hardness minerals); also referred to as conditioned water

solder— a substance used to join pipes; lead-based solder was outlawed in the late 1980s

source water— untreated water that is supplied to a home or business; source water is usually best for outdoor applications like watering lawns


turbidity— water cloudiness caused by suspended particles


volatile organic compounds — organic contaminants including commercial chemicals and pesticides; commonly referred to as VOC's


working water— the water used in a home for most general purposes including bathing and laundering

Trouble Shooting

please click here.

How to recharge a pressure tank:  TEST

Sometimes after a few years of use the pressure tank will lose internal pressure and not empty out all of the water inside the tank. Pressure tanks can last from 3 to 5 years, depends upon water quality and environmental conditions. Here is a way for you to re-pressurize the tank.

Steps to re-pressurizing tank:

1. Turn off water to the unit.

2. Turn off tank ball valve. Open faucet to release any remaining pressure

3. Remove tubing from tank ball valve.

4. Remove tank from under sink and turn the tank upside down in the sink.

5. Open tank ball valve and let tank drain. Sometimes it can take 30 minutes for all the water to drain. You can speed up the draining process by adding air into the tank. If all of the water does not drain out of the tank, it means that the bladder inside the tank has leaked and cannot be repaired. This will happen to all bladder tanks will eventually. Another indication is if water comes out of the air valve.

6. Once the tank is empty, use a tire pressure pump to pressurize empty tank with 7 to 9 PSI with the tank ball valve still in open position.  This puts a cushion of air around the bladder.

7. Re-install/re-attach tank.

AWI warranty: one year full replacement. Second year get 50% discount. Third year 33% discount.

Two things could be causing this problem:

1. Not enough air to create the pressure. The storage tank has a bladder that stores the water and is surrounded by air to create pressure. If this air pressure drops, then the tank will not be able to push the water up. Filling it back up with air using the port on the side of the tank takes care of this problem. Usually, adding 5 - 7 PSI is all it takes. All you need is a bike tire pump or an air compressor.

2. The bladder burst. This is indicated by the same thing. The only difference is that is will not hold the pressure when you refill it with air.

Sometimes after a few years of use the pressure tank will lose internal pressure and not empty out all the water inside the tank. Here is a way for you to repressurize the tank.

How to recharge a pressure tank:

1. Turn of water to the unit

2. Turn off tank ball valve

3. Remove tubing from tank ball valve

4. Remove tank from under the sink and turn the tank upside down in the sink

5. Open tank ball valve and let tank drain. Sometimes it can take up to 30 minutes for all the water to drain. You can speed up the draining process by adding air into the bottom of the tank. If all of the water does not drain out of the tank, it means that the bladder inside the tank has leaked and cannot be repaired. This will happen to all bladder tanks eventually

6. Once the tank is empty, use a tire pressure pump to pressurize empty tank with 5 to 7 PSI with the tank ball valve still in the open position

7. Re-install/re-attach the tank

If the bladder has burst, please let us assist you with the purchase of a new storage tank!

Water Temperature: Usually, the supply line is installed on the cold water line. This is because hot water lines are above the 100 degree limit of the RO membrane. Of course, freezing temperatures will freeze the membrane and cause it to foul.

If your water is cold; try to get a bucket (or something to hold water in) and some extra supply tubing (about 10-15 feet). Coil the tubing in the bucket and fill the bucket with hot water. This will gradually heat the water back up.

For hot water, a chiller before the unit would be okay. You can also use the bucket trick, but fill it with cold water and/or ice.

You can mix hot and cold water (especially if you have the faucet adaptor), but we recommend the bucket method more.

Water Pressure : (Yes, you should get a $15 pressure gauge)

If it's low (below 40 PSI), get a booster pump. They're easy to install and work great. If it's too high without a booster pump, get a pressure regulator. These are also easy to install and use.

Remember; clear housings can only withstand up to 75 PSI. White housings can withstand up to 100 PSI.

Leaks happen all the time. There are many different reasons why a leak would form, but that's not as important as knowing how to stop them. Leaks from fittings: there are a few reasons why a fitting would leak. It could be cracked/broken, it may not have enough Teflon wrapped around the threads or the O-ring could be offset inside the push-in fitting. How you fix it?

- For cracked or broken fittings, they just need to be replaced. We will be happy to send out a replacement for FREE. -(see our warranty page) or a local hardware store should carry them.

- For male threaded fittings, the leak will come out from the connection one drip at a time. This can be fixed by adding 2-5 wraps of Teflon tape. Be careful though, because adding too much Teflon tape will cause the part that the fitting is screwed into to crack (sooner or later).

- For push-in fittings, the leak will be slow as well. Try removing the "collar" that holds the tubing in place and take a needle ( or something small enough to reach inside) and readjust the O-ring. If this does not work, let us know so we can send you a replacement.

- Another thing can happen with push-in fittings. It is not necessarily a leak (though it will cause plenty of water to fly around. If your "collar" is not holding the tubing properly, the pressure from the water can cause it to come undone and spray water everywhere (depending on the pressure) We can send out a new collet (aka the "collar") out for free. Again, most parts can be found at a local hardware store if it's an emergency.

Leaks from the unit: Most of these are due to age. A part might weaken from use over the years. These usually happen without any warning and can cause a lot of water to spill out. Leaks from teh housing are the most common. They can be from a different number of  reasons though.

- Heavy leaks from the top of the housing where the cap and bottom meet are caused by cracks in the housing cap. Most people will think that its their O-ring that's offset, but heavy leaks from there are usually the cracked cap scenario. We can send out a replacement for free (again, see our warranty page first)

- Slow leaks from the housing where the cap and bottom meet are usually the O-ring or a filter. Make sure that there isn't a crack in the cap first to be safe. Check and see if there's any dirt, cuts or kinks in the O-ring. If so, let us know and we can send out a replacement. If it's the filter, just tighten the housing down a little more. Use the filter wrench if needed. Sometimes a filter might be slightly taller than normal, so a little more tightening is needed.

- Leaks around other parts can occur as well. They are less likely, but not impossible. If you have leaks somewhere else, let us know and we'll help with troubleshooting and replacement (if need be)

Again, everything is based upon our Limited Warranty. Please ready the warranty page before sending in a warranty claim.

If water production has slowed down and most or all of the water is going down the drain: This problem is caused by a few things. It depends on the age of the unit and the type of unit you have.

- If you have a new unit, first check the supply connection. Sometimes, it may not be installed properly. This happens especially with the supply valve. Sometimes the needle does not always pierce all of the way through the copper pipe. Also, check and make sure that any flush valves are closed. If these things do not help, check the pre-filters by remove one at a time (making sure you replace the one removed when moving onto the next filter). Normally, it's one of these things that effect new units.

- If you have an older unit, it could be time to replace your filters or the ASOV. If the ASOV fails, it can get stuck in a position to allow most of the water to flow to the drain instead of making pure water. Try flushing off the filters first for about 10 minutes. Also, check and make sure there are no clogs in the lines from anything.

- If you have a drinking water unit with a pressurized storage tank, then it may be the bladder in the tank. Most people with drinking water systems gauge their flow on how it comes out of the RO faucet. If it slows down, it's probably the bladder tank. If not, please check all of the above.

If your water has stopped: Again, this can be caused by a few things and also depends on the age and type of the unit.

- For a new unit, check the lines to see where the flow stops. Again, make sure that all flush valves are closed on your unit. If the flow stops after the RO membrane, remove the fitting that the pure water should be coming out at. Check the Teflon tape wrapping and make sure that it isn't covering the check valve (looks like a metal spring). Try blowing in the fitting from both directions. The flow should be letting the air/water out, but not back in. If the flow stopped before the membrane, check which pre-filter it stops at. If it's still flowing through the pre-filters, but not making it to the membrane, check the ASOV/Permeate Pump.

- For an older unit, everything you check for on the new unit is the same with one exception: the membrane itself. If flushing and checking all the of the lines does not yield results, then it might be the membrane. Though this can be the case for newer units as well (receiving a defective membrane), the chances of that is much less than if you  have an older unit.

- For units with a pressure tank, check everything above. If you cannot find anything wrong with the unit, it may be that the pressurized storage tank bladder has burst. This is a natural occurrence as the tank gets older. Most of the time, this only occurs every 5-10 years of operating. If you have a newer unit (within 1 year), please let us know. Newer tanks should not have that problem.

Please note that the Permeate Pump replaces the ASOV. If you have a unit that's flow has slowed or stopped with a permeate pump involved, these test do not change.

The DI is supposed to remove the TDS completely from the water. Usually, the DI filter is used after an RO membrane for lengthening the life of the DI. Even if the RO membrane is reducing the TDS, you do not know what's in that remaining TDS. If it's nitrates, phosphates, silicates, etc., it could be that it's exhausting the DI faster than normal.

If it's not that, check and see if you are allowing the water to flow too fast through the DI. Normal operating flow through the DI should be between .2 and .5 gallons per minute. Any fast than that and the DI will either exhaust faster or not reduce the TDS down to zero (though it will still be low).

It could also mean that you need a special mix of DI resin other then the 50/50 we use as our mixed bed resin.

A quick and easy test to determine if your DI is exhausting too quickly is calculated as follows.

For example: If your tap water TDS is 200 PPM your water after the membrane should be around 10 PPM. Divide 3000 by this 10 PPM and it equals about 300 gallons of RODI water you will make before your DI cartridge is exhausted. This is for a 10" refillable cartridge. The In-Line DI cartridge will only last half as long. The 20" refillables will last twice as long.

Yes, you do need a TDS meter!

Please contact us if everything checks out, but the DI is still exhausting too fast.