I'm using Salifert for testing Mag. Thanks for the advice everyone. I take it slow with my system as far as adding live stock and the tank is still in it's eary stages. Started up in late December. I'm not worried about the rate that I'm going through Mag, it's was just something I noticed while keeping track of my parameters and dosing. Since I'm so new to this hobby, I was just wondering if anyone else's tanks go through more Mag as well. But as far as my water, I take readings about a day or two after a water change, which is done every month.