-hatchling up to about 250g - 6qt tub, 1 hide, 1 2" water bowl
-juvie up to about 1000g - 15qt tub, 1 hide, 1 3" water bowl
-1000-1500g, and males permanently - 32qt tub, 1 hide, 1 4-5" water bowl
-1500+ females - 41qt tub, 1 hide, 1 6-8" water bowl(or bigger depending on if they have a fetish for tipping the bowl)

And Josh, I know we've been over this before, but once you hatch your own babies, you'll find that they thrive better in the shoebox tubs, especially when you have to deal with non-eaters. If you get the 70qt+ tub that is the long underbed box, even that is plenty of room for even the biggest of adult female Balls. They have no need for those taller tubs that require extra heat to heat up all that air space.