I use crushed coral in my FOWLR
. The tank has been up for about 2 years. I have about a 2 inch layer on the bottom and it looks fantastic. My Chevron Tang loves the different sized pebbles and stuffs to pick up, clean, then toss throughout the day. I credit him with keeping the bottom of the tank PERFECTLY flat and manicured. I have a large skimmer and a good deal of flow and feed heavy. I wouldn't hesitate to use it again. If I was going the reef route with corals that were very particular about water quality, I might reconsider, but I love the look in my fish only tank. The aquarium is at a point of balance now and the crushed coral plays a role.