I think your tank is cloudy because your filter was down, which means your biobacteria are having to build back up and you're likely having a bacterial bloom. It looks more like the cloudyness cycling tanks get than from sand.
I dunno if anyone suggested it, but you should get some amquel or prime and start dosing for ammonia and nitrites until your filter catches up so your fish don't get stressed and sick. And you're gonna need a liquid master test kit to test for ammonia, nitrites, and nitrates to know when it's stable again. The nitrates test is a little tricky, but it's less important than the nitrites and ammonia which are really easy tests.
In the meantime you can add a little salt, 1tbsp per 5g should be plenty, which helps detoxify the nitrites.
And sorry, but I had to giggle at you freaking out over the dead fish

. We've all had fish sucked into the intake and sometimes not even know how.
My when my husband was cleaning a tank once the strainer fell off and a danio swam in ...then three of his brethren swam in after him, and they all got chopped up. I've had fish seemingly commit suicide on purpose by getting stuck in powerhead intakes, even when they had to of used quite a bit of effort to wedge their head in there...
And I've also found fish living in my filters that I had no idea could get through the strainer, in a few cases they'd even grown in there. My MIL had a whole colony of baby bristlenose plecos in her canister filter and accidentally washed most of the down the drain since she didn't have her glasses on and thought they were dirt at first. :\
Others have similar stories. There's been whole threads about it.
