Snails, plants, and fish! Oh my!

Geomancer

I sent an email to the water supply folks, just as a sanity check for what I got from test strips at Petsmart.

They confirmed we have soft water in the 35-45 ppm range (GH).

They say the pH ranges from 7.7-8.2 ... however I get ~6.8 using the API Liquid Test (It is really hard for me to see a difference between 6.6, 6.8, and 7.0). I have driftwood, so I wouldn't be surprised at the 6.8 number due to that, but I get that from the tap also (and the Petsmart strips gave the same reading). Something's fishy here (zing!)

For KH they gave me 25-28 mg/l CaCO3 .... whatever that means?

Quantum

It is expected that the pH in the tank will decrease since the KH (buffering capacity) is low. This is good for your fish, and why I suggested increasing GH without increasing KH. Adding calcuim carbonate will increase both GH and KH (Ca cation for the GH and the carbonate anion for KH) and your pH will likely remain close to that of the source water.