Well, I was really addressing the end result, didn't mean to imply that Ca(OH)2 actually contained bicarbonate.
EDIT - not that I really understand the whole carbonate/bicarbonate/alkalinity/PH thing. It is definitely hard for me to get my brain around it...
I'm worried that if my topoff goes during the day when the PH us up anyway, it might get a little too high. Does the kalk help smooth out the PH swing between day / night? That's the thing I've been trying to address. At night, my PH was getting down around 7.87 to 7.90. I'm afraid that if I just let the kalk go in as topoff, the daytime PH will go higher and the nightime PH will still drop off more than I want.