So I am getting a new tank for my BP and I was curious if he would be good to go in a 30 Gallon Long? I know that is the biggest they should have, but I was just wondering so I do not have to buy another tank in a couple months if he outgrows the 20 I would buy.

He is ~31 inches long and ~580 g

Also, what size UTH should I be getting?

I have heard 1/3 of the tank, 1/2 of the tank. What is the best coverage?