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View Full Version : RO Membranes seem to be failing quickly


amcvay1979
02/03/2016, 11:27 AM
I posted a thread a few months back that my RO was reading high TDS after the membrane and causing my DI to exhaust quickly. Today I checked my DI reading and it was over 20ppm so I thought I should check the membrane TDS.

It too was over 20ppm. This is a brand new Filmtec membrane less than 3 months old. When I installed it the TDS were back to 2 and the output was 2 gallons of pure water and 5 gallons of waste. I made sure to install the correct flow restrictor for the membrane size when I changed membranes.

The only thing I can think of, and I brought this up with my last thread was that the RO was being fed with water after a whole house Whirlpool self regenerating filter and a Whirlpool water softener. Several people told me this was fine and they run an RO system this way as well. Other people said softeners kill membranes, so I don't know what's going on. TDS in to my home is only 120 or so, it's city water so it's not terrible.

Just wondering if going from 0 to 20 ppm TDS in a few months is an indication of spent carbon blocks or if I've fried another membrane? Input pressure is 60 or 80, can't remember, I can look again. Temp is obviously cold for midwest winter but nothing out of the ordinary temp.

Should I remove the flow restrictor and do a manual membrane flush? Is that the correct way to do a manual flush?

amcvay1979
02/04/2016, 10:19 AM
Seems to be a flow restrictor issue. I was sold a 75 gpd inline restrictor and it says 400 on it. Turns out 400 is ml/min and that would be good for a 36 gdp membrane. Going to order a new restrictor that is properly sized for a 75 gpd membrane.

Buckeye Hydro
02/11/2016, 05:08 AM
Feeding an RO membrane softened water is just fine. In fact, when we design commercial RO units where the membranes can run hundreds of dollars each, a softener is a very highly recommended pretreatment. The softener keeps scale from building up inside the membrane.

A flush is very unlikely to change your RO water from 20 ppm to 2 ppm. You have something else going on.

A poorly performing membrane can be caused by an exhausted carbon block, but there are a 1000 other reasons this can happen as well.

We're happy to help with troubleshooting the system. Feel free to call us when you are in front of the system.

Russ
513-312-2343