tank crash?

[TimT]

Originally Posted by Acrowhora

and they seem to be covered in sand.

Since the water went cloudy after the water change and you say there seems to be sand all over the corals I would suspect that there was an imbalance in the Alk/Ca and some precipitation happened.

Other possible causes of cloudy water are bacterial blooms and spawning events.

Recommended course of action would be water changes and test your Alk.

Cheers,
Tim