When putting a fish in the sump, which compartment ?

Basically here is the issue, one of my fish is breaking off pieces of my sps (the more narrow part where the sps is growing). So I am going to assume it is the niger trigger and will test this by putting it in my sump and see if the sps take no more hits. My question to everyone is in which of the 3 compartments in my sump should I put him in?
Compartment 1 is where the water comes down from the main tank, compartment 2 houses the skimmer and pump for the UV sterilizer (largest of the compartments but has the most equipment in it, and the third compartment has the return pump and one of my heaters.
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125ish g Dt, 30g sump, Tek HOT5 48" 4 bulb, Glo HOT5 36" 2 bulb, ER RS-135, mag 18 rp, 4- Koralia 4's, wavemaker, 18 W UV Sterilizer.

Crosshatch Trigger, Niger Trigger, Scribbled Angel, Flame Angel, Naso Tang, Kole Tang, Sohal Tang, Solar Wrasse, Red Coris Wrasse, Purcula Clown, 2 Jumbo Chromis, Lawnmower Blenny, Mandarin Dragonet, 3 Zebra Dartfish. All Fish ~2.5 to 4 inches.
SPS, LPS, Zoas, shrooms, anenome, Coco's, Feather dusters, cleanup crew and cleaner shrimp.
~185 p LR Almost 3y SW

 

id probably do the first, so he doesn't get sucked into anything or chew on powerchords.