Those acrylic arms was actually made for the 8 x 80w T5 ATI lights that was on the tank initially and they were recessed to fit in tight on the euro bracingI do not like that spider legs holding the lights up. It does look a lot better now.
Just a question, how high above the water is your light units now? Recommended height for Radion lights is between 22 to 27cm. Mostly to prevent splashes damaging the units. Had a naughty Regal Tang that loved to splatter water out the tank.
The lights are now 200 mm above the water level.
It is about 20 mm higher than the mounting arms that comes with the lights
My Regal does exactly the same. He always does that in the corner where the feed ring sits, and I suspect he is hinting on some food