Micro feather dusters are indeed a good thing, besides being harmless and pretty, they also remove nutrients from the water (And that's a good thing!)
HOWEVER, make sure what you've got are indeed feather duster worms, and not Hydroids!!!
Hydroids look kinda like feather dusters, but have a firm, smooth tube. Feather dusters have a leathery tube...
I'm sorry I don't have time to find images of both for comparison for you right now, but hopefully someone else can, or I'll try to do so later...
The reason I mention this is Hydroids are definitely BAD, and in my early days I didn't know the difference, and encouraged the *$(@#)@# hydroids to grow and prosper, and boy howdy, have they grown and prosper, to the point that the best I can do now is restrict their growth, I have no hope of eradicating them!
