Did my tank crash! Help!

[neoh]

kalk must be consistently stirred to not allow the sediment to hit the bottom. If you do use an ATO to dose, make sure the pump is in the middle of the waterline, as to not suck up the bottom of the reservoir - if you dump the entire contents of your ATO sludge at the bottom into your tank, this is what you will get. But there are also dangers in this, as it is highly concentrated, you may see a large alk/pH swing, and that's what you should watch out for.

test pH/alk/Ca, regardless of your waterchange.

I would suggest not dosing Kalk unless you need to! You're levels are normally sustained well just by doing regular water changes. Depending on your coral load, you probably won't need it.