RO Membrane question

[Susan Edwards]

from what I've read, the membrane is fine unless you are getting TDS readings. I've just replaced 3 of 4 of the RO filters and going to replace the 4th as soon as it arrives just do them all. With just 3 replaced, I'm back to 0 after a few minutes. Was at 3.

I've had this unit in service since 2016. Even if my tds is 0, should I replace the membrane at this point? How do I tell if the membrane needs replacing. Pressure is between 40-60

 

[homer1475]

Measure the TDS after the membrane. If your not getting 95 to 98% rejection, its time to replace.

heres a nice calc to figure out rejection rates.

https://www.hamzasreef.com/Contents/Calculators/RORejectionRate.php

 

[Susan Edwards]

oh, so just take the in and out to get rate. I think it's okay then. I'll test next time but from what I recall the in reading to be, under 300, then I should be good

 

[Susan Edwards]

Measure the TDS after the membrane. If your not getting 95 to 98% rejection, its time to replace.

heres a nice calc to figure out rejection rates.

https://www.hamzasreef.com/Contents/Calculators/RORejectionRate.php

thank you