How often do you replace your RO membrane.

PatW · Jan 27, 2023

I flush my RO before use. After flush, the water comes through at 2TDS and usually goes to 1TDS after some time. When the water comes through at 3TDS, I figure it is time for a new membrane. I am not sure how much I use per year but a low estimate would be around 1500 gallons. And a membrane lasts me years.

KStatefan · Jan 27, 2023

I do not know what the specs are for the membrane you are using but in my setup my replace schedule is when rejection < 97% it is time to replace. My first membrane last 5 years or so then I started to test some different options.

Fishingandreefing · Jan 27, 2023

Sounds like I will swap out another unit when I bump into a super deal. I have it hooked up to a booster already so really don’t want to just ditch it.

Fishingandreefing · Jan 27, 2023

PatW said:
I flush my RO before use. After flush, the water comes through at 2TDS and usually goes to 1TDS after some time. When the water comes through at 3TDS, I figure it is time for a new membrane. I am not sure how much I use per year but a low estimate would be around 1500 gallons. And a membrane lasts me years.

Per instruction, I flushed 30g and still come out 95% which at 7tds

Fishingandreefing · Jan 27, 2023

thedon986 said:
The aquaticlife systems are known to not be the best. I started out with one in 2016 and realized I was spending way too money on it. I upgraded to a Spectrapure Maxcap system I got a half off deal on. My tap is about the same TDS as yours and I've changed membrane and canisters once in 5 years. I use it to make homebrewing water, have a small 10 gallon and had a 100g system up for a year over that time. When I had my larger system up for about 15 months I was making 30-40 gallons a week as well.

If you choose to keep letting the TDS rise, I would consider some ICP tests every now and then to make sure nothing you don't want is in that 3 TDS. It could be a harmless 3 TDS or it could be something else building up.

Apparently there are lot of people don’t even change them till 5tds. I def need a different unit to achieve that otherwise I would be changing filter once a month. So this aquaticlife is garbage

t5Nitro · Jul 1, 2023

What would a progressive decrease in rejection rate during a single operation mean regarding the RO membrane? Is it no good any longer?

Example: on startup, my system produces post-membrane TDS of 5. Over the course of 3 hours of running the post-membrane TDS is 11. Slow increase over the course of hours in post membrane TDS. Not sure if that's normal or if I hadn't paid that close attention to it until this year.

t5Nitro · Jul 1, 2023

Post RO TDS of 13 now after about 4 hours of continuous running.

Rejection rate of about 98% during the first 2-3 hours and 94% in the 4th and 5th hours so far.

Uncle99 · Jul 1, 2023

t5Nitro said:
Post RO TDS of 13 now after about 4 hours of continuous running.

Rejection rate of about 98% during the first 2-3 hours and 94% in the 4th and 5th hours so far.

Assuming test results are accurate, that’s not what we want to see…..if it was 5…..it should remain 5. As TDS increases, use of DI resin is exhausted quickly.

Likely ok for the moment, but if it continues to rise, that’s a signal to replace.

Mine goes from 5 stabke to around 27 ish seems overnight, then I replace at the same time noticing how DI resins seem to be used, 10x faster than normal.