What effect does high magnesium have on corals?

jasonrusso · Jan 19, 2020

I haven't tested my Mg for a while because I dose reef fusion which has calcium and mg in the same bottle. I tested it today with Salifert and I got around 1800 (1.2ml). My calcium was creping up a little while ago, so I assume that's why the Mg is high.

The reason I ask is because I suddenly lose seemingly healthy SPS corals. My birdsnests will grow like weeds for months, then suddenly stop opening and die. My favia is also not doing well, but I think that's because I had a rogue emerald crab picking at it. LPS corals, chalice, zoas all seem fine.

Greenstarfish03 · Jan 20, 2020

I dont know the exact answer to this question, but I dont think the MG alone would cause the issues your describing. I was running my MG super high around 1800 for several months a while back bc i had a bad test kit and it took me a while to get it down around 1350 and all of my corals were totaly fine and actualy grew well. I have a mixed reef feom sps, lps and softies. I figure something else was weong as well.

Randy Holmes-Farley · Jan 20, 2020

Have you checked salinity recently? If reed fusion was the source, it means Seachem designed or manufactured it poorly. A properly designed two part would not do that.

It might also be testing error. Have you tried that kit on some new salt water?

jasonrusso · Jan 20, 2020

Randy Holmes-Farley said:
Have you checked salinity recently? If reed fusion was the source, it means Seachem designed or manufactured it poorly. A properly designed two part would not do that.

It might also be testing error. Have you tried that kit on some new salt water?

My Salinity had creeped up due to me not calibrating my refractometer. It's back to 35ppt now. New salt mix (LA pro salt) is about 1350-1400.