i set up a 75 gal reef tank in feb. since then i put in about 60lbs of live rock and 60lbs of base rock. i have coralife lights the one with blue and white lights with the 4 lunar lamps. i have a sump with a bag and a skikmmer. my pump puts out 3000 gph, i have it set about half way. the set up has three powerheads set with timers. things were going nice, but then i put in these snails. they were they large type, and everything went bad. i had a manderan goby, yellow head goby, a leather coral, several emeral crabs, about 20 hermit crabs, and a sea rabbit that all died within about a week. i tested the water all is right, but the PH was too high. could this cause the demise of my tank? i had an issue with red algea, my lfs gave me a red slime remover that was a powder and it cleaned it up. could it have been that chemical that could have killed my tank? i still have a tongue coral that seems too be ok, never graet since i go it and a green chromis that rocks. i'm about to back to just fish... please help!!!