Dow or GE

[stoney waters]

Its time to replace my RO membrane. What are your experiences with the Dow Filmtec and GE membranes.

[The Propagator]

The cheapest and most efficient for the price

 

I honestly have no idea which is better but I have an idea they are all probably the same, its just what ever add ons in the media chambers that makes it special?

[reefone]

the dow seems to be the one everyone wants. its also the one im running in my rodi.

[Scott Riemer]

Ok, at risk of HD having a coronary, read what I am writing very carefully.

 

Filterdirect (Water General) claims that the GE Desal (TFC-100/TFM-100) membrane is better than Filmtec. Now, obviously, one must take into consideration that they are trying to sell RO/DI units which have the GE membrane. But, if there's truth in what they say, well, the consumer must decide.

 

we have done extensive testing among different brands of membrane, and we recently have switched to a higher rejection membrane GE Desal membrane, (even better than Filmtec membrane), it removes 97% to 98% of all chemical, dissolved solids in tap water. (replace every 2-3 years) Look at data below.

You can go here and scroll down to read their testing data. >>LINK<<

[Phixion]

I was just about to say something similar to that Scott, wait till Hectic sees this one.

 

But that aside and since we're on good terms now on this, I'll say the same as you Scott, it's really up to the consumer. I can't justify which is technically "better" if one really is, but it is far dependant on factors such as your incoming water condition and TDS. Obviously higher TDS tap going into it will yield a shorter membrane lifespan. I have the Water General with the GE membrane, and so far after just about a year of use, I'm still registering 0 TDS with 2 different HM TDS meters. Yes Scott, 0 TDS... I think the 1 TDS I had before was a fluke with dirty buckets. I washed it out good and how it's back to 0 TDS again, w000!!

[Scott Riemer]

Yes Scott, 0 TDS... I think the 1 TDS I had before was a fluke with dirty buckets. I washed it out good and how it's back to 0 TDS again, w000!!

[HecticDialectics]

Now that I've graduated and work all day, I don't have the strength to argue this as much as I used to...

 

But, the Dow Filmtec membranes are supposed to be better. All I have to say about the Water General unit is that, they claim it has a 97-98% rejection rate, but by their own numbers, (300TDS in, 20 post RO) it only has a 93.3% rejection rate. Dow gaurantees a 96% ... http://www.dow.com/liquidseps/prod/tw30_181275.htm

 

With all membranes, you get a few good ones and a few bad ones. I personally feel that you're more likely to get bad ones with GE, but those WaterGeneral units seem to work well for some people. Others have some problems getting good water out of em without wasting away the DI resin...

 

All that aside, the Dow Filmtec membranes can be had for like $40... which is very nearly the same price as the GE Desal membranes. Spectrapure uses Dow membranes, and Spectrapure has some of the best ro/di systems you can buy, so that should weigh in on everything a bit too imo.

[yardboy]

I feel qualified to answer this question as I've been sourcing RO membranes for quite a few years. Dow Filmtec has been the standard in the industry for a long time. GE has gotten into the water treatment business only in the last couple of years, and only by buying others out. I'm not sure, but I think they bought out Hydronautics membranes, which used to be a quality product when cellulose acetate membranes were the cats meow, but were surpassed by Dow when they developed their thin film composites. The last RO I re-membraned I switched from Hydronautics to Dow.

Of course, these were for 8" diameter, 4 foot membranes, but they are built basically the same as the little ones I use at home. I recently purchased a new Dow for my home system, a 100gpd setup. They claimed 99% rejection. Well, the 285 tds going in came out as 0 tds, which is pretty good. I haven't measured the conductivity to verify their claim, but my previous Dow claimed 95% rejection and hit it on the money, until I got lazy and forgot to replace the carbon filter, then chlorine went to work on it and ruined the membrane. But that was after 18 months.