Moe:
Definately, a pH meter calibrated in April is ready to calibrate again. I had a pH meter stay calibrated for about a year, but others drift in only a few hours. Give that a try and maybe the problem will disappear. If not, read on...
To raise alkalinity with a smaller pH spike, try using the new version of B-ionic. It is based on bicarbonate instead of carbonate:
http://www.esvco.com/prod14.htm
I'd expect that would solve the problem. If not, back off on the limewater and use more of the B-ionic. Since you need more Ca++ and alkalinity anyway, expect to use more, and the new stuff is more dilute, so raise the amount again.
I give advice on how to solve lots of pH problems in this article:
http://www.advancedaquarist.com/issues/ ... 2/chem.htm
Super Cow:
Adding pure bicarbonate will have a short term, small lowering effect on pH when added. In the long run, the tank may blow off some CO2, and the pH can raise later. Also, if you switch bicarbonate for another type of alkalinity supplement, it can have a substantial pH lowering effect. For example, switching from limewater to bicarbonate will result in a substantial lowering of the pH.
The effect of various alkalinity supplements on pH is shown in this article:
http://www.advancedaquarist.com/issues/may2002/chem.htm
Randy Holmes-Farley
