Is this diatoms?? What Clean up crew?

[Exotrezy]

Hello, I started my tank in October and took a 45 day break as I was doing a fallow because of brook. I am using RODI water. Don't know where the start of the diatoms is so I am just planning to get a Clean Up Crew. I have 1 bumblebee Snail that was a hitchhiker from one of my coral. My tank is a 3ft long 30 gallon tank. Let me know Clean Up Crew suggestions. I attached a couple of pictures and 1 video. Also this randomly appeared with 2 spots on one of the rocks about 2 days ago and now its on my sand.
Have a good day!

 

[Exotrezy]

Does anyone know if this is diatoms or something else?