I wanted to add that I went to look at the stock tanks today and decided I'd get the 300 hundred gallon. The dimensions I was told were from the top of the stock tanks I think because the floor space is smaller than the top. I looked up some pond filters and saw the Tetra Clear Choice Biofilters. There not too expensive and come in a few sizes. Would that be ok for the 300 gallon stock tank? If any one can answer these questions and the ones I posted earlier that would be great, Thanks!