I hope you are not serious about a 30 gallon tank. That sav needs much more room than a 30 gallon. For it's current size, I would have in at least a 4 ft x 2 ft x 2 ft. enclosure. When it gets about fully grown(which could be in 4-6 months if cared for properly), the monitor will require a fairly larger enclosure(I would go 8 ft x 3 ft x 3 ft minimum) to be properly housed.
I would also watch it on the 'fattening up'. If not fed properly, savs are prone to obesity....which in turn leads to fatty liver(and/or other issues) and eventually death.
I suggest picking up a copy of The Savanahh book by Ravi and Bennett. It is the best out there and will give you a much better understanding of the animal.