Changing an RO membrane on a dual RO membrane unit?

[Laith]

Haven't been able to find any info regarding this...

When you have two RO membranes running in series on an RO/DI unit and you start seeing your RO output water TDS start to rise, eventually you are going to want to change an RO membrane.

But which one? The first or the second one? or both?

And does it make sense to do the same thing as you do with dual DI cannisters (but opposite): switch the first one to the second position (the one getting the highest TDS water, ie the waste water from the first membrane) and change the first one by putting a new one in the first position?

It seems a bit of a waste to change both membranes when there could still be life in one of them?

 

[Fishy212]

Trial and error my friend, when you do it long enough you really start to figure out all the kinks. No harm or foul trying to get the most out of your equipment. Look into getting additional canisters to save the life of the RO membrane.

 

[mann1139]

I run two membranes in series, and I have not figured out the optimal way to change the membranes yet. Usually I just go by when the TDS fails on each.

That said, I run a 75 in my first, and 50 in my second (and I may drop that to 25 if I can find one). The second membrane sees a lot less flow, so it doesn't need to be as big as the first.

 

[Phil D.]

I run 2 also, and just change both when needed.

 

[Laith]

I run 2 also, and just change both when needed.

I guess that's the only way to be sure... ;Happy