I have a 120. My Aquatic Life T5 makes a lot of algae on the glass. I've gone to using only two bulbs on a 6 bulb fixture. It must have good reflectors because my Odyssea 4 bulb did not make so much algae or kill purple coraline. I was looking at a long spined Urchin and wondered if they are good at cleaning the glass on the aquarium. Secondly I keep Triggerfish in that tank. A Blue Jaw, a Niger and a Picasso. Would any of these hurt the urchin? Lastly whats the minimum tank size for a large melon size long spine urchin?