Yes, Calcium and Total Hardness are pretty much the same thing. With your problems you should be chlorinating with bleach or liquid chlorine. Each 121 oz jug of 8.25% bleach should add about 2.6ppm of chlorine to your water.
It's not difficult to maintain and keep clean a pool with a CH of 400 and a CYA of 100. But you DO need the K-2006 test kit, or at least the K-1515 single test to maintain it.

I think you need to spend a little time learning how our BBB system works and how you balance chlorine, pH, and CYA levels to keep it under control.

However ONE thing is true: It's virtually impossible to follow both our advice and a pool store's as they will contradict each other many times. However, we have the documentation and the science (chemistry) and the empirical results of tens of thousands of happy pool owners to support our methods.