Switching to plastic

Im wanting to switch from glass to plastic for my bp, he's a juvi(24 inches) and growing like crazy what size tub do you guys think would work?

anything from a 32 qt to a 41 qt would be good. Although with him that size you may want to go with the smaller of the 2 or just buy them both for when (if) he outgrows the old one.

thanks for the help aric.