Do I need a new membrane?

[Fishbro]

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?

 

[NS Mike D]

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.

 

[Water Dog]

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.

 

[Opus]

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.

 

[Fishbro]

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 efficientoy.

It doesn’t come with a meter installed but I have a external meter. The TDS from my tap is 328 what should I expect it to be after the ro stage?

 

[Opus]

It doesn’t come with a meter installed but I have a external meter. The TDS from my tap is 328 what should I expect it to be after the ro stage?

I would look for 8 or below.

 

[Water Dog]

It doesn’t come with a meter installed but I have a external meter. The TDS from my tap is 328 what should I expect it to be after the ro stage?

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.

 

[Water Dog]

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.

 

[Fishbro]

Ok and should I replace all the filters before flushing the membrane? The filters I know need to be replaced but if they are old as well as the membrane it for sure wouldn’t read 8 or below.

 

[Fishbro]

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.

Yes for sure.

 

[Flippers4pups]

If the membrane got dry, replace it.

 

[Fishbro]

If the membrane got dry, replace it.

Yeah it stayed wet I’m just wondering if I should replace the carbon and sediment filters before or after flushing the membrane.

 

[Flippers4pups]

Yeah it stayed wet I’m just wondering if I should replace the carbon and sediment filters before or after flushing the membrane.

Before.

 

[Opus]

Ok and should I replace all the filters before flushing the membrane? The filters I know need to be replaced but if they are old as well as the membrane it for sure wouldn’t read 8 or below.

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]

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?

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]

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.

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.

 

[Fishbro]

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.

Yeah my unit will be using two carbon filters.