Dropping Magnesium?


New member
Previously on other tanks I just did a weekly WC and didn't really test anything. On my current tank I spent the money and bought ALK/TRATE/CALC and MAG tests.

Now I know that coralline will consume Calcium and Alk, but I find that even with bi-weekly 10% WCs, and Using saturated Kalk (2tsp/G) in the auto topoff, I can't seem to keep up. Especially with Magnesium.

I've been testing my parameters weekly and keeping a log, and I seem to have gone from 1350 MAG to about 1050. Bumped it up a bit with some ESV Magnesium. ALK stays pretty stable at 7.7dKH though I do add Reef Builder weekly. Calcium is also being used, but I'm right out of Calcium supplement to bump it up at the moment.

My question is, what uses Magnesium? I have an LPS/Soft dominated tank.

Randy Holmes-Farley

Reef Chemist
Premium Member

You might also check your salt mix. Some run low and if so, water changes can bring it down. :)

You can use MAG Flake deicer to raise magnesium on the cheap. :)