why so much mag

[Proteus]

I'm wondering why my tank.is.using so much mag. I use rb salt which is low already. But am dosing 12 ml a day now up to 14(slowly raising) I'm loosing about 280 ppm over a week while dosing (tm balling)

Alk 7.7 salifert
Cal 420/450 elos

Ihave.been experiencing som stn on acros but am chaulking it up to new zeo regiment and low mag