I have always been told to use the general formula of .....front + side = length of snake........as a general way of determining an appropriate floor size for a snake. Of course this varies from species to species....and so does the height. That tub might be a little small for a bp that size. I use 41 qt Sterilites for my large bps. They meausure 35" x 17" x 6". The extra height is not needed with ball pythons and just gives you more air to heat IMO.