My mg has been low for a while and despite dosing seachem reef advantage mag weekly, now double the dose that should raise my level, I can't raise it above 1150. So what to do? Because apart from the impact on my tank, and the frustration, it's getting costly. To my eyes nothing seems to be suffering, and even tho my calcium is also low at 350, corals and coraline algae seem to be doing fine. Ph is 8, Alk is 9.5.