Anyone have sand in your tanks? I have a HOB filter and a sponge filter in my 55. Lately I've been moving things around in my tank and I think excess sand is in the HOB filter; it's making a grating noise, like something is in the impeller housing, probably big grains of sand. I've rinsed it out many times, but it's still making that noise. Anyone have a trick for getting the sand out?