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Dow Filmtec is a brand of membrane. Most vendors use them in the 75 GPD version and they are the number one choice. Its the 100 GPD Dow membrane you want to stay away from not the 75. The 100 is NOT a RO membrane but is in fact a much less efficient nano filter. Nanofilters are not approved in the US by ANSI/NSF for drinking water since they do not reduce bacteria and viruses to what is considered as safe level for human consumption. Thye provide what is called 2 log removal where a RO membrane provides 3 log removal.
Dow Filmtec provides bulk membrane materials to other membrane winders like Applied who then wind or produce their own versions similar to Dows. Both Applied and GE Water sell what thye consider to be a 100 GPD RO membrane which is basically identical to a Dow Filmtec 75 GPD RO membrane. The difference is in they way the rate the GPD production. Both GE and Applied say it takes 65 psi and 77 degrees to produce 100 GPD. If you put that on a graph it shows they produce 75 GPD at 50 psi or 90 GPD at 60 psi.
Now Dow Filmtec says their 75 GPD membrane gets its rating at 50 psi (see the similarity with the GE and Applied) and 77 degrees. Again if you graph the Dow it shows it produces 90 GPD at 60 psi and 100 GPD at 65 psi. Its all in how they juggle the numbers. Dows 100 GPD nanofilter puts out 100 GPD at 50 psi and more like 125 GPD at 65 but the kicker is it is only 90% efficient where their 75 GPD is 96-98% efficient. Don't even consider the 100 GPD Dow as it will eat your lunch in DI replacements.
If you want the best RO membrane consider Spectrapures 90 GPD SpectraSelect series RO membrane. It is the only 100% individually hand tested and guaranteed 98+% rejection rate (efficient) RO membrane on the market. Spectrapure hand tests every one of them and then stores them wet in a special solution unlike anyone else. This process produces a very efficient membrane, mine is averaging 99.23% over an 18 month period and still going strong. You pay more initially but the savings in DI resin is amazing. Combine the Select membrane with Spectrapures proprietary hand blended DI resins like the MaxCap and SilicaBuster and you have a system that cannot be touched by anyone. Years of testing and research have paid of for them.
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