Low pH/alk in new tank

[pturner]

I have a new tank I'm in the process of setting up. Its a 36 gallon corner bowfront with nothing but water, base rock and a DSB of 4".

My pH is at 7.8-7.9 and alk is 7 dKH. When I mix RO/DI water to add the pH is at 8.2-8.3 but the alk is still 6 dKH.

I don't understand what could be causing this and I hesitate to try and solve a problem I don't understand by just throwing products in. There is nothing living in the tank (as far as I know) that could be respirating and producing CO2. I haven't done the bubbling CO2 test yet, but I don't think that is the case as I have a VERY large amount of plant life in the house as well.

Please advise!

[Randy Holmes-Farley]

Excess CO2 often comes from your home air, not just the tank organisms. Most people do not have nearly enough plants to offset people, pets, and gas appliances.

I'd suggest trying the aeration test described in this article:

Low pH: Causes and Cures
http://reefkeeping.com/issues/2004-09/rhf/index.htm

Most likely, if you just select a high pH alkalinity addition method once you begin to supplement alkalinity, you won't have such low pH.