Although a little detritus can help plants, it sounds like you have too much, if those detritus type animals are running rampant. Too much detritus can also be breeding grounds for pathogenic bacteria, that cause disease in fish.
I had/have some, hydra, I only wish they got really huge. 5 pound hydra, would look awsome. Only in salt water, the sea anemones are a similar creature.
An algea scrubber, will greatly reduce their numbers, all things being equal. Over feeding, detrus, is blooming bacteria, which hydro mostly thrive on.
Its hard to vaccuum. I am growing 4 leaf clover carpet. It havent been easy. Its not fully rooted and i think my bichir keeps knocking it out. Almost every other day i need to replant some. Its the only plant i have that im having trouble with.