Tiny Black Bus In Res?

This is not my grow. This was shown to me by a friend.

In his res, there were 4 or 5 quarter size formations of almost microscopic black bugs floating around. If you looked real close you could see some of them darting around.

I have never seen this before and my guess is it is caused by his grow environment, straight up ghetto grow (tin foil on the walls, poor ventilation, 90+ heat, no air stone in res, all packed into a small bathroom). I know he is using 25 gal. flood and drain system, GH nutes, GH FloraKleen and SM-90 (used incorrectly). Been searching all the forums with no luck, any help would be great.

TIA

BIT

tiny black bus? holly shit...were there any survivors?...jk
...at first i thought nats...but darting around in the water?? idk...he needs to drain that thing...wash it good, like with some bleach...rinse it very good...and put an air stone in the water.

Make sure to keep the light out...if you can get a cover on the res. it helps alot too.

LOL. (No survivors) Just noticed the bug misspell. We drain and cleaned the res with bleach, I'll check it again today. Thanks for the reply.

It's the larvae of gnats that are feeding on his roots