Okay, since I was getting disagreement between my two Ca test kits, as suggested I took a water sample to my LFS for them to check. Strangely (but preferred, I guess), the very old sera kit, which gave me a reading of 420 was closer to correct than my month old SeaTest kit which read at 300 or so.
So, the LFS found that my Ca was at 380 and KH was at 11. My lack of understanding of water chemistry and options continues to show, but I am not sure what to do next. If I am understanding things correctly, my course of action needs to be to continue to do a stepped up routine of water changes until my KH and Ca are in line on the balancing table that Kipass4130 posted earlier in this thread so that, ideally, Ca is at 420 and dKH is at 8.4, and only then should I start again using my C-Balance 2-part solution. If I am understanding this correctly, to start using C-balance again now would likely maintain or raise my Ca, but would also maintain or raise dKH, which I still need to lower (based on my present Ca level), perpetuating my "out of balance" system. On the other hand, *IF* my current Ca were 380 and dKH were at 2.8 or so, THEN it would be reasonable to use the C-balance to slowly raise Ca *AND* dKH to their target levels. BUT, since I am still out of balance, a balanced product is not the way to go for now.
Am I getting it, or have I missed the boat somewhere?? Is there a better course of action for the short term to balance my system other than water changes?