you said it was your first time adding calcium, then your third time....you change the water weekly, but gravel vac 3x a week..... i'm not trying to be mean, but i'm confused. if noone has accurate information then they can't help you. how do you gravel vac without changing water? when you do a water change, how much do you change? did you treat the water before adding it to the tank? is it the first time you added the calcium, like you said in your original post?