White specs in water?

[DcoarM]

Hello all,

I have a couple of videos to upload here, but my tank has been up for a month and a half and I have a lot of white specs in the water? The first with all flow eliminated in the tank. The second has one powerhead on low. I had a buddy say they think it is micro bubbles, but those would be gone if there was no flow.in the tank. So what does R2R think?

 

[T-J]

I'm guessing sand.