So I’m picking up a BRS 6 stage rodi system up and the person I’m buying it from said the membrane is about a year old with 8 months use and 4 months just sitting. The 4 months it was sitting, it was sitting wet inside the canister. Should I replace the membrane or can I just give it a good flush?
Do I need a new membrane?
- Thread starter Fishbro
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NS Mike D
In the arena.
Only one way to tell and that is to read what the TDS meter at the end is saying.
Aside from that I would drop in a new membrane for a used unit regardless. No reason to take a chance since the goal is to make o TDS water in the first place.
You have no idea how much water ran through the membrane nor how much TDS it had to pull which affect the lifespan of unit.
Get a new membrane so you have a solid starting point. And if the unit doesn't have one, plan on adding a meter you needn't guess if the unit is doing what you got it to do.
Aside from that I would drop in a new membrane for a used unit regardless. No reason to take a chance since the goal is to make o TDS water in the first place.
You have no idea how much water ran through the membrane nor how much TDS it had to pull which affect the lifespan of unit.
Get a new membrane so you have a solid starting point. And if the unit doesn't have one, plan on adding a meter you needn't guess if the unit is doing what you got it to do.
Do you have a TDS meter, or does the unit come with TDS meters installed? A Dow Filmtec 75 gpd membrane (standard with BRS units) will give you between a 98-99% rejection rate. So if you know what your TDS is from the tap and what the TDS is post RO membrane but before the DI stage, then you can calculate if the membrane is still running efficiently.
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Opus
2500 Club Member
If it doesn't have a tds meter you need to get one. I prefer the handheld ones. Get a reading of your tap tds and then after the ro membrane. Should be running around 97 or 98% efficiency. If it was kept wet you should be ok. A membrane should last 4+ years under normal usage. I would get new pre filters and new DI. Also get a copy of your city's latest water report if you are using city water. You need to know if they are using chlorine are chloramines. That will dictate which kind of prefilters to buy.
Opus
2500 Club Member
I would look for 8 or below.
By the numbers, if we assume a 97-99% rejection rate, then your post RO TDS reading, based on 328 TDS from the tap, should lie between 3 to 10 TDS.
Remember, when you start it up, disconnect it from the DI stage and let it run for a few minutes before you take a TDS reading. You want to be sure to flush out and bypass all the high TDS creep water before taking a measurement.
Flippers4pups
Fins up since 1993
If the membrane got dry, replace it.
Flippers4pups
Fins up since 1993
Before.
Opus
2500 Club Member
The prefilters will not affect the tds. They are strictly there to protect the membrane. The main issue right now for you is you need to know if your water has chlorine or chloramines. That determines which type of carbon filter to buy. If the unit is using 2 carbon filters then you are probably fine. Chloramines is really only going to affect the di usage.
Miller535
Valuable Member
I am assuming it's probably a 75 gpd unit, a new membrane is like $35, I wouldn't risk it. I would just replace.
Opus
2500 Club Member
What is he risking? He has a tds meter and can test the tds before and after to determine if the membrane is still working. Asl long as it was kept wet as the previous owner claims, it still should last him 3 or 4 years.
