Siphon as much of it as u can and do a 25 percent waterchange I got it after slacking on water changes I did a 50 percent n after a week it all was gone
As long as you only feed as much as they can eat nearly completely in under a minute then once a day is fine. If you don't have a cleanup crew, then get one appropriate for your size tank. A lot of places sell packages by tank size. It will help a lot.