Are you feeding flake or frozen?
IMO, too much food.
If you already have high phosphates, the only way to get them down is with a GFO like Phosban. The phosban reactor and media are pretty cheap - well worth the results you'll see in the long run. Then you can help keep them down by reduced feedings (by not putting so much back in the tank).
We use essential cookies to make this site work, and optional cookies to enhance your experience.