Help! What is this pink dust?

[atc1]

I have had my tank for over 2 years. It is a 20 gallon tank. I have always struggled with the nitrates even when everything else is perfect. For the past couple months I have had this pinkish fine dust covering my live rock. I have tried to determine what it is but haven't seen anything exactly like it. Any ideas on what it is and how to get rid of it. I have also been trying to eliminate what I think is diatoms in the sand bed but they returned as well. Any help is appreciated. Thanks!

 

[Mechano]

Could be some type of dinoflagellates. On the sand bed it could be Dino’s or diatoms. Hard to say without putting a sample u see a microscope. It’s just a guess.

 

[formallydehyde]

Sand bed definitely looks like diatoms, you could just get something that eats them like a small conch. The dust on the rocks just looks like detritis with maybe some fine sand mixed in.