Need Help Identifying

[ubiq]

These little white encrustations are covering everything in my sump. They're very hard and almost impossible to scrape off. This is a shot of a reactor pump after 3 months. Thanks in advance.

 

[EeyoreIsMySpiritAnimal]

The photo is a little blurry but I'm pretty sure those are spirorbid worms. Harmless filter feeders but, as you've discovered, somewhat difficult to remove especially from plastic.