cloudy water overnight

[Rhythmmakers]

what's happening to my tank at night? my tank is thriving but for the last few weeks when the lights go off the water is turning milky white and the tank smells like everything in it is dead.
At first I thought I was going to loose everything. loaded it up on charcoal, added extra filters, doing what ever I could to battel what ever was happening. I figured something was dying.
the strange thing is the skimmer was not affected, the fish looked fine and testing the levels were all good. this clears up in a day or so but keeps accruing. this same situation has happened in another tank of mine about a month ago and has stopped. basically the same tank corals and fish but totally separate.
for now the lights are only off for 2 hrs. per night to avoid this.
any thoughts we be appreciated.

 

[olonmv]

It’s a bacterial bloom. I dosed seachem prime when I would get blooms and usually would clear up within a few hours. Some use UV sterilizers to mitigate the issue.