Water filter

[sen5241b]

Someone gave me a 5 stage water filter. It outputs TDS 25 water. Is there some way to tell what stage filter needs replacing?

[Big Country]

I would test the water after it comes out of the membrane before it go to the DI and see.  Chances are that it needs a new membrane

[madweazl]

Does it have a single stage TDS meter or multi? Typical 2 way meters measure after the RO membrane and after the DI resin. If you're getting 25 after the RO membrane your tap water is extremely high (unlikely) or the RO membrane is spent. Color changing DI resin is often used so you know when to replace it (turns a tan/brown color). 

Edited August 20, 2018 by madweazl

[Jon Lazar]

You should replace everything. 

 

You definitely need new DI and a new RO membrane.

 

The sediment filter and carbon block exist to protect the expensive membrane. It doesn't make sense to spend all that money on a new membrane and not replace the relatively cheap filters. If the carbon filter is clogged or exhausted, your new membrane will be ruined by the chlorine in tapwater. 

[sen5241b]

All good info. I did not know chlorine can ruin an RO membrane.

[madweazl]

You mentioned 25 TDS but how long was the system running when you read that number? It will start higher than normal when you first turn it on and drop down to near zero within a minute if it's operating properly. 

[sen5241b]

You mentioned 25 TDS but how long was the system running when you read that number? It will start higher than normal when you first turn it on and drop down to near zero within a minute if it's operating properly. 

 

 

I discarded the first half cup and then filled a half gallon and tested it. 

[flooddc]

If you are using a handheld TDS tester. Make sure you collect test rodi water directly from the rodi hose and use a brand new cup. Otherwise your reading will be higher than it should be. 

My reading directly from the ro reservoir always read 5-10ppm. But reading in a new cup that taking directly from the rodi reads 0.