I've been running my sps tank for a year and a half and I've dumped about 100 lbs of magnesium into the tank. That seems like a lot to me. I run zeomag in my calcium reactor along with ARM? I don't know why. This is just from experience. I use Littlesilvermax's Mg mix.

I agree, I have to dose a lot of it to keep up with the demand. I even try to keep the coraline algae to a minimum because it can be a big sink for mag.