100GPD 5-Stage RO/DI system


  • 100 gallons per day (4.16 gallon per hour)
  • Assembled and ready to use out of the box
  • 5 micron Sediment filter included
  • Two 5 micron Carbon Blocks included
  • 100GPD CSM membrane with 98% rejection rate
  • Color changing DI resin cartridge included
  • Clear acrylic housings to see cartridge conditions
  • Automatic Shut Off Valve included
  • Designed for water pressure as low as 40 PSI
  • 2:1 waste ratio
  • All fittings included to install in various configurations
  • Filter housing wrench included
  • Drinking water as well as Reef Water from the same system
  • Add TDS meter for $29.50
  • Add Pressure Gauge for $30 
  • 1 year warranty


This unit is very easy to install with quick-connect fittings. I wish all plumbing was this easy! It takes about 10 minutes to hook up, and you can start making pure water for your reef tank.   
The written Installation Instructions help you step by step!  (or watch the video below)

It can be installed wherever you wish. You need a cold water source, and a drain for waste water. Indoors is best, in a temperature-controlled climate out of direct sunlight. 

Notice the DI that is hanging separately from the rest of the unit? Along with the full system, I provide a "Tee," an extra cut-off valve and some tubing, so that you can enjoy great tasting drinking water. For your reef tank, use the water coming out of the DI filter.

This unit sells for $249! That may sound expensive, but think of the benefits:

  • Pure water available any time, day or night.               
  • Convenience, especially in emergency situations!       
  • Less problems with nuisance algae                             
  • Lower alkalinity readings. (Lowered water hardness)

You can.... 

  • continue to buy RO water from the supermarket, and trust their filters are being changed in a timely fashion.
  • buy RO water from your LFS for .50 a gallon, but you have to lug the containers back and forth. Please test their water!
  • use tap water and add "Prime" (by Seachem) to dechlorinate your water, but each bottle of Prime will cost $10 or more.

Or you can bite the bullet and install one of these units and have water available any time you need  
it. In the winter, I'm able to make 5 gallons of water in 85 minutes. In the summer, it takes 52 minutes to make the same amount, as the source water is warmer. The tap water in my area has a TDS reading of 277ppm. After the RO membrane, it reads 7ppm. Finally, after the DI cartridge, it reads 0. Pure clean water for the aquarium! The RO membrane rejection rate for my personal unit after 44 months of use: 97.5%

How much money will you continue to spend buying water and dechlorinators? It won't take long for you to break even, after that you are saving money making your own water. I figure I spent $60(plus tax) a year for Prime to treat my tap water. After 8 months, I estimated that I'd made 615 gallons of RO/DI for the four aquariums in my home. Buying that much water from the LFS would have cost me $246 plus tax, and that was for a period that was less than one year!

Buy one today!

[nd_video url="https://www.youtube.com/watch?v=-XVjoJDWG7Q" different_values="0"] [/nd_video]

Every system comes with all filters, membrane, filter wrench, DI resin and fittings - ready to use right out of the box!

Because there are so many opinions about the different units made by different manufacturers, and because many hobbyists debate what is better and what is necessary, below are a few observations for you to consider:

Question: What are the specifics about each filter, and who makes the membrane? What type is it?  
Answer: The unit comes with a 5 micron sediment filter (the white filter), two 5 micron carbon blocks, a 98% rejection rate PuROMaxTM membrane that is good for 3 to 5 years, and a color-changing DI resin cartridge.

Question: Is there any benefit to running two DI cartridges?  
Answer: No. The first one will do all the work, the second one does nothing. When the DI cartridge is spent, it needs to be replaced. If your unit produces 0 (zero) TDS, the water is pure. You can't get more pure than pure. (The only 'benefit' of running a second DI is if you don't change the first one. The secondary DI would act like a backup. But you can see the cartridge change colors to help you know when it needs to be changed.)

Question: Does the membrane need to be flushed? Do I need a flush kit?  
Answer: No. This is more of a sales device than anything else. You can buy a flush kit, but the flow restrictor needs to be replaced. Units running for 10 years are still working great and have never been flushed. It is not rinsing off the membrane.

Question: How can you tell the carbon filters need to be replaced?  
Answer: Test the water that comes out of the unit for chlorine. If you read anything above 0, it is time to change them out. You can buy that test kit from any pool supply store.

Question: How often should I change filters?  
Answer: The sediment and carbon filters should be replaced every 6 months. The DI should be replaced when it is depleted, and this varies depending on the water quality in your area.

Question: How long will the RO membrane last?  
Answer: 1 to 5 years is pretty common.

Question: Why are some units white? I can't see if the filters are dirty.  
Answer: The clear acrylic housings are more costly to produce, and are a little more brittle, so care must be given not to overtighten these...or drop them! They will last for years and years with proper care. The white ones are stronger, and last much longer, but you are right about not being able to visually inspect your unit. Relying on a TDS meter, a chlorine test kit, and taking note of the length of time it takes to make your water will be good indicators. A good policy is to just replace the filters every 6 months.

When your source water is very cold, RO units tend to slow down in production rate. They are designed to run with water that is closer to 78° F, which just happens to match our aquariums. Here's a trick that may get things back up to speed during the colder months:

Replace the tubing that leads from your cold water pipe to the unit with a 25' long piece. Coil as much of that tubing inside a 5 gallon bucket and fill the bucket up with water so the coils are submerged. Put an aquarium heater in the bucket and set it to 78° F (or hotter if necessary). The heater will keep the bucket water at that temperature, and that water will warm up the water traveling through the tubing to your RO/DI unit. Production rates will jump back to normal.