Feather Duster Bloom
So, my tank has been running for 2 almost 3 months now. The first rock I got was covered in a good but of coraline, a ton of aptasia, a few feather dusters here and there, and some other worms and bugs. I got the rock a day after I got my aquarium set up and filled. Since then, I've gotten rid of the aptasia(except one last one that is bein a pain to get rid of), and the little bugs died off I'm assuming as I never see em anymore. My aquarium has been being ravaged by diatoms all over my new rocks, the substrate, and the filter inlets/outlets. After doing a water change/substrate clean today, I noticed that my oldest rock is absolutely COVERED in feather dusters, but not only that, my substrate (caribsea white sand) has a good amount of them popping up here an there on it, mostly concentrated in the middle though underneath and behind a shelf I made.
My question is, is this normal for featherdusters to be taking over like this? I've read the diatoms are, so I'm not worried about them. The feather dusters though I'm not sure if they can harm anything when they're in a large enough population. As far as I know and read, they're just filter feeders. Has anyone else had FD's pop up like this?