yep, it tests total hardness...and there are some known issues with the test that have been discussed on the forum before so it is not the most accurate. It is not what you need. You need a calcium hardness test such as the one in Ben's test kit or a taylor K-2006

As far as acid goes, use muriatic...comes in gallon jugs. Be aware that this is just another name for hydrochloric acid so have some repect for it.