Cheato is a fast growing macro but that really doesn't apply to the set up in the tank.
This creature does need room to swim and the ball of cheato take up 1/2 of the already undersized tank.
let's take a look a little closer. I am 2 1/2x's bigger than you, that is just the dt alone, not including my 40g sump and 20g refugium and I still have phoshates. All my fish together probably have less of a bioload than the trigger.
You need to get rid of that bad boy.