A 90 gal is huge for an adult ball python...I'm not saying it couldn't work, but just something to keep in mind - lack of security causes stress in ball pythons. Like with many reptiles, the effects of stress don't necessarily kick in overnight. Pay attention to your snake's behavior...is it thermoregulating properly, or is it spending ALL of its time in one hiding place? Sometimes balls that are in big tanks like that feel too vulnurable and pick one spot to stay in...and won't venture out to seek heat or cool off in favor of feeling safe in their "spot." Over time this can cause them to stop eating, get sick, etc.
Just some food for thought. Ball pythons really don't benefit from a lot of space, as much as you think they'd like a roomy tank, they would really prefer the security of a smaller one.