KH has fallen and can't get up
About 4 weeks back after a 60% water change, for whatever reason, I decided to add about 2.5 or 3 tsp of MgSO4 to my 50g tank. I think I thought that since it was in the proper range according to Chuck Gadd's calculator, no problem. Well, the KH went from a steady 4, to 2. Is my KH ever going to get back to 4 with water changes(it hasn't yet after 3 50% WC) or am I going to have to add some calcium carbonate?