I have a 36" x 18" x 18" Exo Terra PT2613 terrairium that should be here Tuesday. This is a new tank setup so I'm doing things a little differently this time. My question is how long does my tube need to be for a tank that is 36" long. I'm looking at using an 18" reptisun 10.0 tube would this be suitable or should I go for the 24" tube?