How measure PH?

[Brent F]

Thanks, Untamed. The article you posted explains why most additives increase PH while baking soda lowers it. I was using the calculator at http://home.comcast.net/~jdieck1/chemcalc.html to find a product to increase alkalinity for my tank based on the effect on PH and where my PH is.

This whole post started because, without knowing my PH, I wasn't sure whether to use baking soda or a comercial product to increase alkalinity (or maybe both?)