been a reefer for 7yrs. 2 yrs ago had a tank crash. i had a great reef in my office 55g (sump hang on refug. mh) it actually looked like a garden with lots of lps and softies,shrooms and leathers, fish etc. had a sea apple get to close to a power head and got sucked in and macerated. if any one doubts the toxicity of a sea apple talk to me. between clients , 15 min , my tank was destroyed. even tho i did a complete water change at noon i loss all my corals except the softies. a few fish survived.eventually even removed the rock and put in spare rock that was not live just extra from other tanks that had been stored dry. assuming it would slowly become live rock i added fish and a few shrooms. the tank has no sand just some shells and small rock on the bottem. it is a desert. added a few pieces of live rock from clients tank that did not help. no corraline algae. i use ro/di water. lots of water changes that is 5 gals every other week by the way there is only three fish very colorful and nice looking but nothing else. is my only recourse to totally break down and go thru the purchase of more lr. i have probably one hundred pounds of imported dry rock from other tanks. i would like to try to use that. sorry about the length of the post. by the way repeated testing of water q always was within the parameters that most experts recom. thanks