Switching from MVB to a tube UVB

[ReddyFreddy]

Firstly let me apologize if any of this has been covered in depth. I checked the stickied post and did a quick search of the forum but wanted to ask in case I missed something. With summer here and on the advise of some members, I have decided to switch from a 100 wtt MVB to a 75 watt normal. However I now need a UVB source. In the past I used a 18" T8 draped at an angle across the tub, as recreated in the picture bellow. However I was looking at buying a T5 HO and was worried that doing that would result in the light being to close to my Russian, as the table is only a foot high, not including substrate? Is there a way keepers normally mount these lights? Also what size is appropriate? The Table is 4 foot wide, so should I go with a 48" or a 36"?. Thank you all.

 

[Markw84]

I always have to give the disclaimer = the only way to know for sure is to measure YOUR situation with a solarmeter 6.5. All we can do is guestimate based on other applications. Just like asking what height will give 95° at a basking spot with a 75 watt bulb. We can estimate based on our experience, but a thermometer is the only way for you to know for sure! It is even more so the case with UVB and a solarmeter. So many things can vary - type of hood, type of reflective surface nearby, and even bulbs themselves will vary. I really wish the price would not stop so many from using this important tool.

SO....

Why not stay with a T8? Sounds like the best fit for your situation. A 10.0 t8 will "normally" be good at about 10". A high reflective hood will change that though. You would "normally" need to keep a 12.0 HO T5 at about 18" - 20" with a hood. Even without a hood at least 14" - 16", but you would then have to be careful not to look into the bulb when looking into the enclosure!

If you want to go the T5 route, most simply build a frame that attaches to the sides, or front and back, with a bar across that you can hang the fixture from. You will want to do something like that anyway as the heat source needs to be fairly close to the UVB source to stimulate basking behavior and have the basking happening with the UVB at the desired level. In your "mock up" you wouldn't have that and there is nothing to draw your tortoise to the area where the UVB is, and the tortoise would not naturally want to just sit in a bright corner with nothing to draw it there.

 

[ReddyFreddy]

Would a 30" t8 be ok on a 4 foot wide table 12" above the substrate? The 18" worked well on his old table but that one was smaller, so when he was basking he was right by the UVB. If a frame is needed for a larger tube regardless, then it seems it would make sense just to upgrade to a t5