Huh?!! You’re thinking diatoms and I’m sure that’s what the op has not Dino’s… have you put them under a scope @blecki ? Dinos don’t come and go with sand or silicates..Yes, obviously so. Dinos feed on silicates. Beach sand is mostly silica, aka, the most abundant substance on the planet. Even argonite sand has some in it.
I like engineer gobies so don't really have a choice, but have to admit when I ran the tank bare bottom I had a lot less issues. Just had to suck out the mulm every once in a while.