Has anyone tried converting a crushed coral substrate to a deep sand bed without removing the crushed coral first? I know that there is advice out there that says you shouldn't do it without removing all crushed coral first. However, the advice doesn't seem to be based on first hand experience. If you had an inch of crushed coral, cleaned it and put three or four inches of aragonite sand on top, what would be the problem? If no one has first hand negative experience, I might try it and report on the results. I have a 75 FOWLR that is a few years old and is doing well but nitrates are between 20-25 ppm and I'd like to knock them down a bit....