The CB-70 is 41 quarts.

It is large enough to house the majority of females unless you have a true monster. Males may never need this size and will do well in 32 quarts. I personally only use one hide in my racks. I use blank newsprint as substrate and they can moved the hide around to where they want quite easily.

What exactly are you using has a "humidifier" in each tub? Just wondering as I've never heard of anyone doing this in a rack.