Ok, i have a 55 gallon tank that used to be home to a red eared slider (turtle) for a long time. it was only filled about 3/4's full with water, and over the years it built up quite a layer of thick white mineral deposists (i was using an aqua clear filter, and the spray from it would leave the sides encrusted) i have the tank outside and have filled it from the hose, and scubbed off the thick stuff, but there is still a layer on there (above the old 'waterline') that leaves a slight forsted haze. my next step is to scrub some more, drain it, scrape it with a razor, then refill with R/O water and soak it again for another week and scrubb and stuff. question being, if i use this tank for an octo, if there are still deposits left, with this be at all harmfull to either salt water fish, live sand, coral, and of course the Octo? i dont want to use any chemicals for cleaning it (CLR of stuff), but i am worried that all of this will not come off?