Bacteria bloom? Anything in there capable of spawning? Macro-algae crashing?
This exact thing happened to me about a month ago.that night everything looked super, the next morning BAM!! just like your pics. I think something spawned. I didnt loose anything but I had been away it would have been bad. If I knew what spawned I would remove it.
It looks like something died. You didn't have any turbo snails did you?
Its pretty easy to tell if something has died. Does the tank have any strong odor?
Sea cucumber maybe? Have one? Mine will spawn from time to time at night, and make the skimmer go crazy, but I haven't noticed the water getting cloudy.
Maybe kalk if you use that. I had a reactor get clogged up one time for a few days, then when it unclogged itself, the water level dropped enough to dump around a gallon of kalk in the tank. It was cloudy like that, but luckily I didn't lose anything and have since quit using kalk.
If the junk your skimmer is overflowing smells funky like mine did I would guess that it had to be something organic like a spawn or something pretty big died