Adding DI to RO unit?

[roger]

When I originaly bought my RO unit I got an additional seperate stage that has a re-fillable DI cartridge in it. I originally used it for peat and may actually go back to that.

The problem or question that I have is this. My RO water comes out fairly pure (the tds has been slowly drifting up over time) but the pH is just about dead on 7.0 and its fairly stable under most conditions. Would adding a DI cartridge to the mix drop the pH of the output water. Im hoping to be able to have a ph of 5-6 so that I dont have to treat the water to drop the pH.

Though I think in the meantime Ill hook back up the peat cartridge and see what that does for me.

Peace,
Roger

[RandalB]

Roger,
Sorry bud, but the pH will still be 7.0 through a DI. The more pure the water is the closer to 7.0 it will be. You just won't be able to read it accurately.

If your TDS is drifting it may be time for a new membrane. Give it a good flush, change the prefilters and if it stays the same, it's time for a replacement. The TDS drift is the first sign the membrane is going. The fact that your pH is staying stable also means that something is getting past the membrane unless you are doing a RO/Tap mix. Ro water tends to mimic whatever you are mixing it with. So if you are adding acid to it, the pH drops quickly.

Peat filtering the RO output is a good way to drop the pH without using the more harsh acids.

JMO.
RandalB

[roger]

Hello Randal

I was afraid you where going to say the DI wouldnt help me any.

Ill need to check but last time I looked the tds had only gone up about 5% from the original value.

Guess Ill play with the peat when I get home and see how it goes.

Peace,
Roger