I bought some fluorite substrate and on the bag it said rinse before putting into aquarium. I rinsed the substrate for an hour and the brown stuff would not rinse out. It also said on the bag the brown dust would settle after 2-12 hours, so i put the substrate in my tank and filled it up. It is still brown after 48 hours. It looks like sewage. I dont know if i should call the LFS and tell them or what? Any suggestions?