Alk/dKH

[Harpo1966]

What kind of alk/dKH readings should I expect on my City water & from my RODI? I was told that my RO membrane needed to be replaced because it was allowing high dKH readings.

My city tap water has a dKh of 5
My RODI has a dKH of 1.4

What do you think

David

[Mackie]

oddly enough i just tested my DODI water last nigt and also got about 1.5 (I do have a new RO unit) on the way as my old one is ~ 13 months old. Dont know if this reading is normal or not.

[chuckreef]

You should use a TDS meter to monitor your RO memebrane and uour DI column outputs.
RO out should be less than 10
DI out should be zero, replace the resin cartridge as soon as it changes (reads 1).

[seapug]

It will vary depending on the overall quality of your tapwater, but the lower alkalinity of the RO output is probably tied to the low pH of fresh RO water. If you test it, the pH of your RO water will probably be lower than your tap as well. That is related to the high concentration of CO2 it usually contains. I'd assume the alkalinity drop is caused by the same thing.

[bertoni]

RO/DI water should be at zero alkalinity. Your membrane and DI cartridge both likely are shot.