Magnesium problem

I've been dosing calcium and alk with the b-pink and my calcium has been low this whole time. Alk is around 10.5 and calcium is always 400 or below. My alk is where I want it but the calcium is too low for me. So I tested mag and whaddya know, it's 1180. Can someone suggest ways of raising it and the max ppm's raised daily? I've heard of the Epsom salt but does sulfate really affect a reef that badly? Thanks