Microscope ID on Brown in Sand

[loftreef]

Tank is around 1.5mo old, I had some brown splotches start to appear in the sand maybe 2 weeks into my cycle. These never went away (although they have come down a bit).
I picked up a crappy handheld microscope for ID, but these dont seem to match anything I can find on this forum/youtube. This was a sample I took from sucking some up and letting them settle in a small vial. They re-constituted into some brown on the sand that came along for the ride, and this sample is from a brown cloud that formed above the sand. They swim quickly in a corkscrew motion and dont circle around an anchor point like I have read about with dinos. The microscope is supposedly up to 250x. At 100x I can barely seem them and at 250x they are still tiny, much smaller than other 100x pictures I have seen. I dont entirely trust this microscopes magnification specs though.

Nitrates: 17.5 (salifert)
PO4: 0 as far as I can tell (Salifert)

Also, prepare for the worst microscope video you have ever seen(sorry): https://www.youtube.com/watch?v=zsDtgn3QvQw

 

[gbroadbridge]

You're unlikely to see anything useful with anything less than a student grade microscope.

At 1.5 months, it'll just be diatoms - which will go away on their own

Dino's are extremely unlikely with your Nitrate levels.

 

[loftreef]

thanks @gbroadbridge

My curiosity is getting the best of me... is 250x enough to see nitrifying bacteria? Is this enough fidelity for anyone to take a shot at what these are? You would be saving me the money of buying a proper microscope to satisfy curiosity

 

[taricha]

These are not a dino. They are another random harmless flagellate. Something like a cryptomonas / rhodomonas.
Here they are in a couple of vids from my system, shape and movement a lot like yours:

(Close-up):

 

[loftreef]

That looks exactly like them, thanks @taricha