Over the weekend I found my Mg was reading around 800. I thought my Red Sea test kit was off so I went to my LFS and they did not have a Mg test kit to test my water so they gave me a bag of their water that they said was 1390. I tested the LFS water and with my test kit their Mg was around 1360. I've been dosing Mg throughout the weekend and brought it up to 900 last night which was spot on to the amount I dosed with the Red Sea Mg supplement for the last 2 days. As of late last night here are my readings: Mg - 900ppm Alk - 7.5dKH Ca - 440-460ppm Salinity - 1.025 My tank is a 20g with 10g sump. Total water volume around 25-27g. I forgot which salt mix I use but I also did a 20% water change the day before I tested which confused me on my readings. I had a feeling something was off since a couple SPS frags haven't had the normal polyp extension and the Coraline stopped trying to take over all the glass. Is there anything else I should be doing other than dosing to get the Mg up?