Fish poop...really??
Squirt some Kent’s microvert in the tank once a week...just a little, what feeds filter feeders feeds algae too. You don't need to squirt it right on it or anything, just in the water. They need a gentle flow not high water flow. Feather crown should gently sway in the current.
I really hate to be a nag but….
In the future,
NEVER purchase a single critter until you have done your homework. You avoided disaster this time but who knows what you might bring home next. Impulse buying could be very harmful for the rest of the critters in your tank. Before you bring home anything, you should already know how to feed it, where it likes to live, sand or rocks and most important how big will get and what does it get along with.
When it comes to saltwater critters, some things can actually poison the tank if it feels threatened by other tank mates, some critters are so dang mean it could kill every fish in the tank. Some critters need special lighting, like an anemone, some need special diets, like live food only or copepods by the thousands a day. Some tiny little fish may grow up to be huge.