It was hitting the glass for awhile but I removed about 20 pounds of rock and several corals last weekend to let it spread out some. In the 2 years I've had it, its growen about 4". From my experiance its really not that fast of grower like many say, I do have a calcuim reactor and keep the calcium in the low 400's and 2x250 halmiton 14k's. I'd say it grows a little less than a 1/4" a month. I still have a couple years in that tank, I'll just have to remove more rock and corals which I don't mind since this is my favorite thing in the tank. I'm am planing a new tank in the summer of next year. I planning on a 180gallon 24x24x72, that should be good for several years.