In the next week or so I will be buying an RO System. I really don't know much about them other than that I need one to have clean water for my fish. It has become a pain to pick up water now that I have a 135 gal tank. In fact I have started to cheat and use tap water with primer, which is horrible. My poor fish...

Anyway as I look at the RO systems is there anything that I need to look for and anything that I need to avoid? I am hoping to find one on craigslist. In fact I saw a 5 stage 50 gallon unit for $80 that I thought I would look at. Any suggestions are greatly appreciated.

I will also be purchasing a ro water for my freshwater planted tank 130gal. I've been doing a lot of reading on them and it seems that just because it say's 50galon per day dosen't mean thats what you'll get. Many factors like the current quality of the water, water pressure, temp etc. are a lot of factors that limit your output. There is ro ro/di & units with pressure pumps. It's all kinda confusing. I do expect to pay $200.00 for a good unit. Something with a filter that is easily replaceable and readily available. I'm going to have my well water tested by a local water purifier company and get there recomendations and test results , then hit the net. E-bay had some nice ones. You can also ask your local pet store what they use.

the filterguys.com are reef hobyists that sell good units. Airwaterice.com is where I purchased my 5 stage unit. Both their sites have good information on typical units and what is important in an RO unit. I have dealt with both companies and can vouch for their customer service and overall knowledge. Both companies specialize in RO / water filtration NOT just selling equipment.

Hope that helps.

+1 for air water and ice

Things you want to look for:
1. A name brand RO membrane such as the 75 GPD Dow Filmtec or 100 GPD GE Water/Osmonics or Applied Membranes. These three are basically identical in every way including GPD and water quality. Dow says 75 GPD at 50 psi, the other two say 100 GPD at 65 psi, lay the graphs over each other and you see they all produce 75 GPD at 50 psi, 90 GPD at 60 psi and 100 GPD at 65 psi, all at 77 degrees F water temperature.

2. Low micron rated prefilters. 1 micron or less is better since it does a better job of protecting the downstream carbon block which is the next item.

3. A single 0.6 micron carbon block is all you wil need. Don't fall into the "stages" or more stages is better game. The reason some vendors still use two carbons is they use a high micron prefilter which makes the first carbon in line act as a secondary prefilter which exhausts its chlorine adsorption ability. Stick with one low micron carbon block like the 0.5 or 0.6 micron Matrikx+1 chlorine guzzler.

4. A full size vertical refillable DI canister and cartridge. These hold 20 oz of resin and have far superior contact time to horizontal filters which can channel or short circuit.

5. Name brand housings and fittings. Ebay type systems use no name Chinese knock offs which may appear similar but are not tested for quality , working pressure or more importantly bursting strength. Often the plastic is inferior and wil not stand up to even household use. Most of the vendors like the couple already mentioned and others like Buckeye Field Supply, Ltd. , Purely H2O the leader in home and aquarium reverse osmosis and ro di systems! and SpectraPure Water Purification Products all use high quality housings and fittings.

6. A capillary tube type flow restrictor is prefferable over a fixed type since it allows you to fine tune your waste ratio for optimum performance.

7. Things like a RO bypass valve, inline pressure gauge and TDS meter become necessary very quickly. I am not a fan of inline TDS meters even though I own two of them. I use the inline as a rough guide only and rely on my handheld TDS meter for accuracy. Both are made by the same company HM Digital but the handheld COM-100 or TDS-3 runs circles around the inlines.

8. If you plan to use the unit in an autotopoff situation an autoshutoff valve is needed, if you use it manually you won't need one. If you want to use the RO for drinking and other uses a drinking water kit is a good option or Buckeye sells a reef quality system which also provides drinking water too.=, some of the others may too but make sure its a reef system adapted to drinking and not a drinking water system adapted for reef, big difference.


I use only Spectrapure myself personally because of my poor tap water quality but the 75 GPD premium from Buckeye is impossible to beat for $169. None of the others comes close.

i am also gett a RO/DI system soon i just thought i would say i am getting one from bulkreefsupply.com
you should check them out i have herd great things about them and know quite a few people that run them

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