what is your MAG testing out? Ideally you want it around 1350-1400, to combat bryopsis you want to be somewhere around 1600+

Also MAG typically stay constant after reading...Doesn't drop like CA daily. Also you do not want to raise your MAG by more than 50 points at a time. So don't jump from 1300 to 1600 it should be evenly stretched out 4-5 days worth of MAG dosing.