I think the 3 foot dimension in the metal stock tank might be a little tight. I'd go for the round one. There is a company called High Plains Plastics that sells plastic stock tanks in a cool green color and also blue. It's a good option if you're avoiding the poly tubs because of the black/ gray colors. They are slightly bigger and cheaper than the Rubbermaid 300 gallon stock tank at 350 gallons and $158 vs. $240 (Lowe's quote).
:What do you guys think about a 300 gallon metal stock tank for an enclosure, for a 100lb ally? It is 3'x8'? or a 6' round metal stock tank at 395 gallon? I think John Richards houses some of his monsters in metal stock tanks?