View Full Version : When to replace RO Membrane?

10/27/2011, 09:12 AM
I have this on my OceanReef +1:

I would like to know how often do I replace? I have changed the 4 cartridges once since last membrane.

10/27/2011, 09:23 AM
Everyones water is different. If you get 0 TDS readings after your filter changes then you are safe by what I have read. Your TDS will tell you when it's time.

10/27/2011, 09:37 AM
I am getting +2 after DI and will be replacing all four filters, which are on there way. I really wouldn't want to order a $45 membrane.

10/27/2011, 11:32 PM
Membranes generally last two to three years and either stop producing water or your rejection rate falls away and you start going through resin more quickly. If your not having problems with your membrane stay with it. It only takes us two to three days to get another membrane into your hands.


10/28/2011, 12:35 PM
+2 is nothing to worry about. Your DI has probably fully changed colour ? In fact you could probably change just the DI if your filters look fine. Either way replacing all will surely put you back to zero. Membrane sounds fine.

10/28/2011, 12:39 PM
I will change it until TDS before DI is double digital

10/31/2011, 09:34 AM
Thanks guys for pointing out my short coming in my answer. We get into a grove with so many one on one emails in a day we overlooked the number of readers on a forum thread. I tried to answer DiazE membrane concerns since he indicated he had filters ordered which indicated his intention to change filters.

Carbon and sediment filters may give no outward sign of exhaustion. Low volume drink water filters can exhaust very quickly, remember we are filtering both waste and product water. The filters we sell are high capacity, top of the line chosen for large volume aquarium water production, not glass of water production. Our recommendation is to change filters once ever six months, nine months if your making smaller volumes of water. We believe two stages of carbon to be superior, allowing longer carbon contact time and preventing disinfectant break through. Municipal water plants can change disinfectant levels from day to day and two stages handle higher levels better. Chloramines filtration is always an issue as it breaks down carbon very quickly and single carbon systems are short on carbon contact time and weak in capacity.

DI resin should always produce zero TDS and should be changed at a reading of no higher then two to three. The color changing resin can change color and still produce zero TDS but exhaustion is near. Once resin is exhausted it starts throwing back what it has stripped off and readings can climb quickly. Low pH tap water in the 7’s can contain high levels of CO2 which has no TDS reading and can cause rapid DI exhaustion.

We recommend using an inline TDS meter as they are always at the ready and don’t go into the junk drawer and go unused. You have no idea of the quality of water your producing without a meter.