MVBs and fluorescent bulbs can work in larger tanks.
But that's only because a larger tank gives you the room you need to provide a proper gradient of uv from the basking zone to the cool zone.
What nob fails to mention simply because he doesnt agree with it is that lighting experts and herp experts recommend areas in the tank with little to no uv radiation so that the animal can escape the rays if it wants to. You shouldn't have to force an animal into a hide to escape the rays as nob suggests.
<<< Going to an area of zero unshaded UV and going under a hide achieves exactly the same thing regards going to zero UV .
<<< One of the reasons we all provide hides to our pet lizards is this as well providing them a place where they have privacy from prying human (and other pet's) eyes.
You can see in the first chart that he posted, the manufacture put lines in the chart to show you a good range for that bulb. And that range includes the low uv areas. Because unlike nob, the manufacturers understand the importance of a gradient and levels of 0 in the tank.
Nob also uses outdated charts which is borderline unethical imo. He is aware the manufacture has changed their recommendations yet he continues to use the old charts.
<<< please stop MISREPRESENTING my option and making FALSE claims, there is copious proof on this board in many posts that what you are claiming is incorrect , all available for EVERYONE to see IN CONTEXT.
Brandon , your baiting has to stop as does the personal attacks.
If you feel the need to contribute , keep it factual and directly on the question asked , keep personalities out of it. ( Jeez now I'm coming over like a mod …. apologies to the mods .)
Unfortunstely, in your case, your tube is almost as long as your tank. Even though your tank is quite tall, there most likely isnt going to be an area where your uv gradient can get to 0. If your tube ran only half the tank or so, that would be better.
OP stated VERY CLEARLY
wide:61" deep:28" high:24". I have a mercury vapor uvb10.0 (100W) heating bulb and a long fluorescent 46"(12% uvb, 30% uva)uvb lamp to cover my tank
So his tube is 46/61 of the length of his tank (75%) which is fine PROVIDED it has one end right next the MVB ( behind or infront of it like this PLAN VIEW )
If it's like this
A picture says a 1000 words and shows everything succinctly and clearly.
It is likely the UV spread from the end of the T5HO will create a low UV zone (perhaps even a zone at very close to zero UV). If the UV tube is more than 12 inches from the cold end of the tank , the UV in the last 8 inches will be very low (near zero). This can be confirmed by looking at the iso-irradiance charts published here http://www.uvguide.co.uk/fluorescenttubereflectortests.htm
that look like this :
Of cause Brandon is welcome to take some measurements using a Solarmeter and check this or disprove this.
If the OP can tell us how from the cool end of the T5HO tube and it's reflector hood is from the end of this tank it will not be a huge task checking the UV iso-irradiation charts and checking the level of UV at the cold end of the tank the UV will be OK if a good gradient is provided from basking spot (HIGH) to cool zone (LOW) as indicated already, a hide will help , but better off rearranging the lighting..
Here is arcadias new recommendation for our dragons.
Note how they recomend a uvi of 4-6 only at the basking area, with a gradient down to 0 on the cool end of the tank. This is what leading lighting experts suggest, this is what manufactures have suggested, and it's what has worked for decades.
>>> clearly shows in the new guide that a 24 inch tall tank requires a T5HO 14%UVB in a reflector hood to produce adequate UV at both the basking spot and in the cool zone.
If you can make your mvb work with the tube, that is perfectly ok. Just dont be misguided in the thinking that your whole tank needs high levels of uv throughout it you need uv at the basking surface, and a gradient of decreasing uv to 0 throughout the rest of the tank. UV is harmful, just as much as it helpful, and our dragons know when they need an escape, make sure you're providing that option.
-Brandon