I am have a lot of trouble figuring out why I can't get rid on nitrates and pospates, I have done many water changes once even draining the tank and starting over still no luck anyone ever heard of your sand holding nitrates? I have soaked the live rock for 3 months changed all the water nothing in the tank for 3 months they just want drop last resort is to remove all the sand any ideas? in closed is a pic of the tank not a very good one