New enclosure...

[CooperDragon]

That's a nice new big space! I'm sure he will enjoy it. The T8 is a bit low power for such a large enclosure. You will need to create a branch or space large enough for him to bask that comes within 6-8'' of it and provide basking temps for it to be effective. Ultimately you'll be better served by a T5 with a reflector that can sit 12-14'' above the main basking area and still provide daylight levels of UVB. They are absolutely worth the investment.

https://www.amazon.com/Sunblaster-904296-NanoTech-Fixture-Reflector/dp/B00AKKUBDQ/

https://www.amazon.com/Zoo-Med-26061-Reptisun-Fluorescent/dp/B00AQU8HAO/

 

[CooperDragon]

Yep, The fixtures are 24'' but the end caps take up some space so a 22'' T5 bulb is appropriate for a 24'' T5 fixture. This is a great combo as well (and is what I use) http://www.lightyourreptiles.com/22-t-5-ho-fixture-high-output-with-arcadia-d3-12-ho-bulb/

 

[CooperDragon]

They are both quite good and pretty similar in output. My Arcadia has lasted 3 years so far without needing a bulb change (output measured regularly with a Solarmeter) so I can say they have great longevity. Your mileage may vary though.

I'd stick with the 10.0 or 12%. The 14% is a newer bulb and quite strong. Best suited for very tall tanks. The 12% will provide adequate UVB levels at 14'' but if you can build a branch or something to allow access closer to the bulb if desired that may be a good idea.