I have a 30gal tank for about 2.5 yrs. all was well for the first yr or so, then all the Phos, Nitrates and ammonia went sky high. Fish and coral dong fine. But new fish did not make it. Got new test kits as I thought they were old. Did a number of water changes - no luck. I read where the sand might be contaminated so I dumped the whole tank and started over with new sand and distilled water. I re-introduced the coral, rock, and fish. its been 3 days so I tested the water. The same results everything high. I am not an expert an don't have all the hi-tech sumps. I have an in-tank filter with charcoal and a sump on the back of the tank. Any help is appreciated.