Small crawly bug with two black dots

[RobsReef2020]

I removed all rocks and fish from my reef tank. I left about 5 inches of water in tank. I noticed the amphipod and copedpod population increase. I also toniced a small black and clear bug that crawls on the sand. I found hundreds of them in a remote corner. They do not look like the copepods on the glass. What could they be? Daphia?

 

[tzabor10]

These pictures are not in focus. I wish I could help more

 

[RobsReef2020]

Here are additional pictures and video. They are slightly longer than the grains of sand.

 

[ISpeakForTheSeas]

My first thought would be some kins of ostracod, but I really can't say for sure from the pics - sorry. If you can get some microscope pics or some strong magnifying glass pics (think like a jeweler's loupe), I may be able to give a proper ID.