RODI membrane lifespan?

[HiddenClown]

How long can I leave my RO unit off before my membrane goes bad?

[sditch]

Heavy usage could be 6 months, meduim to light could be one year. Just depends on how well you flush your membrane and how much water you treat.

You should have a good TDS meter for both the input and output TDS going though your membrane that will help give you a indicater when you need to replace it or flush it out.

If you do not have a TDS meter then if you are going though your DI fast then its most licky your membrane is going....

Hope this helps.....

[HiddenClown]

its a 24GPD unit and I might get 7-10 gal. a day so, now my question is how do you flush your membrane?

[jdieck]

THe average lifespan of a membrane is three years but as mentioned above it depends on your input amount of inpurities, if it has ever got dry and flushing.
My inlet has around 130 to 150 ppm and I flush after every use. THey have been working for 7 years now and still maintain over 99% rejection.

To flush the membrane you need to install a by-pass valve to bypass the membrane restrictor. Flush it for a couple of minutes after use.

By the way, the volume of production is not a reliable indication of membrane deterioration as the volume is very dependant on the incoming temperature and pressure of the inlet water. If your inlet pressure is below 60 psi the production volume is significantly reduced.

[HiddenClown]

where can I get a by-pass valve?

[jdieck]

try thefilterguys.biz

[Amphiprion]

I run the same sort of regimen as jdieck. I also flush out all new carbon cartridges (and replace them regularly) and use .2 micron absolute sediment filters. Even after 2 years of use, TDS out of the membrane is still zero (verified by multiple meters).

[AZDesertRat]

You should not leave a membrane dormant for more than 10 days to 2 weeks. There is the potential for Nasties to grow inside them after a period of non use. If you must leave it down for extended periods it is recommended you remove the membrane and store it in a sealed bag in the refrigerator with some DI water in it.
Non use is probably harder on a membrane than heavy usage due to the fact it sits for long periods in high TDS water. No amount of flushing in the worlld will bring it back. Large municipal systems get around this by using chemical treatments but we have not got there yet for small systems.

[crvz]

I've had mine last 4-5 years before replacing it, and even then I didnt think it was totally necessary. The other filters and DI resin get swapped out considerably more frequently, but the membrane enjoyed many years of use.