THe Schuran media is great! I hope that you have seen a big difference now that the tank is on autopilot. The internal pH of the reactor should be around 6.2 to 6.3 to effectively utilize it. As a bonus, go to a garden center, buy some dolomite, but about 5 to 10 percent of the volume of the reactor with the dolomite and your Mg will never falter.
I like the new set up and love your centropyge!