I have a 75 gallon fowlr tank that has been up for about 2 years. I have had nothing but trouble with this tank. Long story short i decided to clean tank yesterday. Toothbrush to rock and vacuum out detritus. I stirred up sand a little with the vacuum but worse the circulation pump must have become dislodged overnight and blew the sand all over. Yesterday i did all the testing i could and sg 1.025 nitrate 40. Nitrite 0. Amm .25 and ph 7.8. Today i did another 5 gallon water change and now nitrates are 80! My coral beauty was dead this morning but my other fish are still ok. 2 pajama cardinals, 2 clowns, 1 4 inch yellow tang. I dosed with prime yesterday and with todays water change. I just dont know what else to do!