Purified water - carbonic acid

[karburn]

Things like this make me wish I'd paid attention in chemistry class. I have a new Kent Deion 200R unit, and the pH of the purified water suprised me. I ran about 10 gallons through just to get the unit working, and then I sampled the next batch. With a freshly calibrated meter: 3.09. I realize than carbonic acid is a by-product of the purification process, but this pH totally kills my plan to rig up a top-off valve from a sump to the DI unit. I expected to have to buffer and aerate the new water some, but not his much. Is that pH to be expected, or should I be contacting Kent Customer Service? Thanks

[Anthony Calfo]

Although low (and depending on the quality of membrane/resins used, plus quality of source water)... the acidic pH you have observed is very common for demineralized water. Pure Di/Ro water is almost never to be added directly to an aquarium (else it will be a burden on the buffer pool, etc). It can be dangerous at times.

All such purified water is to be at least aerated... and usually buffered/remineralized too before using as evap or salting for wc's.

We have much on this subject (rendering RO or Di water for use) on wetwebmedia.com. Likely quite a bit of archived threads on good message boards like this too... do search for your consensus, my friend.

Anthony

[karburn]

Thanks. I guess I was not specific enough in my search (which I always do before starting a new thread) Forgot about WWM, though. I'll start there. Thanks as always.