Yes, pickling lime. I'm thinking of running a controlled experiment like Jim, though: one 150 tank just like mine (running lime drip), and another 150 just like mine (but running official Peter Wilkens Kalkwasser drip). First I need some angel investors to float the venture capital. Anyone game? Or maybe I'd better just get a 300 gallon and drip lime on one side and KW on the other. Then I'd have a much cooler tank, and my results could support any theory I wanted to believe in! He he.

Seriously, I don't know on the alk support. IMO, any impurities in the pickling lime should affect Ca addition and alk addition in the same ratio (esp. given recent articles by our teacher Randy on RC). Bottom line for me is I wanted both a CaCO3 reactor and a KW reactor online in my system, so I don't care that the KW drip is leaving alk just a little low. I'm still waiting on my 2nd dosing pump, so I can get everything set up (Minh's recent experience has helped me resist the temptation to do it faster by using a float switch).

Dean