Whats wrong with this tank?

[2poor2reef]

Good job aesop. You're doing the right things. It's tough to work on two different problems at the same time. If it were me I would continue to focus on the alk.calcium problem and then deal with the cyano afterwards. While yopu probably have a nutrient source somewhere, low alk can also contribute to the problem IME, and the alk/ca is probably what's killing your corals. When you say the ca dropped versus shat you measured in the mixing container I assume you allowed for the dilution caused by the existing tank water right? Depending on how large your water changes are, you can only do so much at once. Get your alk right which it sounds like you have. Then raise your calcium to at least the high 300's. Then attack your cyano. If you notice it is primarily in low current areas then get some supplemental water movement in that area. Good luck.

 

[Mouse]

Havn' read all of the threads so im sorry if im repeating someone else. But make sure you get your makeup water up to alkalinity also. I use Tropic Marin Re-Mineral M. Otherwise whatever your adding to the tank will be removed with water changes.