How much do you dose?

[Zoaelite]

Only unseen solution I can think of is your calcium is elevated causing calcium carbonate precipitation thus lowering the alk. That being said if your corals are growing like weeds I doubt your levels are wonky.

I have a feeling your deficiency is due to a whack load of coral, I was dosing near 150 ml of both solutions when my 120g was running. Might be time to choose yourself a fancy little reactor.