After a recent water change I added Calcium Up to get my levels in the 100 - 150 range. I seemed to have a harder time raising the level up than in the past. It would rise very slowly and took the whole container. It also left a grit all over the walls of the tub.
A week later, the calcium is down to 25 and despite wiping down the sides the grit is still there. I had thought that calcium levels, once raised usually didn't fall that drasticly.
My ph is at 7.6 and the TA is at 75. Any ideas on why this may be happening and how to get my walls smooth again? Thanks.