I bought a 185 gal used tank about 3 months ago with water and sand included. I did not wash the sand I was worried about getting the fish back in the tank before something happened to them. So now all that said as to what I did not do please tell me what I can do now to get the nitrates under control. I can't get them under 80 I have done 4 water changes at about 50% each time. Every thing else is good. Ph,ammonia, nitrite,salinity,temp. I put a bag of chemi pure in it as well. I use ordi water. What else can I do now. I am thinking of taking the rock out and washing it and maybe even the sand should I do this or not? Please help I don't want to loose my fish. It's a FOWLR tank.