ro membranes

[littlesilvermax]

What about the Filmtec 75 gpd membranes. I always thought they were top-notch.

I have two left.

[fencer]

Mark is essentially right there are only a few manufacturers no doubt that DOW relabels some of there RO filters to other companies. If I bought an RO filter made in say Afganistan I might wonder about the quality. I was told most RO membranes have a lifetime of at least 2 years or more depending on the duty. What will shorten the lifetime is excessive differential pressure cause by plugging or chemical decomposition(which is why you have all that prefilter), or by the booster pump. I imagine the only way you can tell is by TDS monitoring or if algae starts blooming in you tanks for no reason. You can buy pharmecutical grade RO membranes for $$$$

[littlesilvermax]

I have gone through 6 membranes in my reefing history.

I have always used a dual TDS meter.

I have found that the Filmtec membranes stay at 0-2 ppm twice to three times as long as the other ones I have had.

I know it is not a conclusive test, but membrane number 2 is working great for me now.

[fencer]

I forgot a high conductivity is also indicative of a failing membrane, so add a conductivity meter as a useful tool