UVB Bulb Placement

[Toni17]

Hi, I am thinking of building a 48x24x20 enclosure for when the dragon gets bigger. They (two girls about 3 months old) are currently housed in a 30 gallon long. I've been doing a lot of research on enclosure builds and I can't decide if I want the UVB lighting on the back wall or on what will be the ceiling and also what size bulb should I get, an 24-inch or a 36-inch. Which will emit more light? Ceiling or back wall? Where did you place your lights?

I already know that I will be placing two ceramic fixtures (one for basking, the other for heat emitter).

 

[Tyler_Vance]

I would get the 36" and center it, that way whether your dragons are basking or cooling off they can get there UVB rays still. For the heat light just keep it close to the UVB on one side so he can get heat and UVB in the same spot.

As long as they can get within 6" or so of the UVB light and temps are correct you should have no problems!

Post pics of your build!

 

[Toni17]

I bought a TV stand at the Salvation Army that I will be converting into an enclosure. It came with glass doors so all I have to do is mount the light fixtures.

 

[jarich]

It needs to be on the ceiling of the enclosure, not the back wall. The reason for this is that UV rays can be harmful to their eyes over time. They have adaptations to account for this in the wild, with their bony brow ridges and eye lids that stick out a bit. So putting the light at the ceiling above them means these adaptations can be utilized and there should be no problem with their eyes. If you mount it on the back wall, then you have light shining directly into their eyes as its at a lower angle than their brow ridges protect.

As for placement, you want to have the basking spot and UVB over to one side generally speaking. You are not just trying to create a hot spot and a UVB area, you are trying to create a gradient from an area of high heat and light to an area of low heat and light. In the wild these things come together in sunlight, so high heat means high UV too. As a result, these two lights should be side by side, as close as safety allows. Place them both to one side as then you can create a nice long gradient from one side of the enclosure where it will be hottest and with highest UV exposure, down to the other side of the enclosure where it will be coolest and have little or no UVB exposure.

 

[Toni17]

Jarich, I understand what you're saying. As for the UVB placement, should I mount the UVB fixture horizontal to the doors (length) or to the left or right side of the ceiling (width)? Photos of enclosures I've seen have the UVB fixture mounted on the ceiling towards the back wall with the basking light next to it. I've seen UVB fixtures mounted diagonal. Off to do more research.

 

[Toni17]

I may have just go with a Mercury Vapor Bulb. I will only have to replace it once a year. With the tube, I would have to replace it twice a year and in the end it will cost the same as a Mercury Vapor Bulb. Plus, I won't have to worry about UVB placement and all that stuff.

 

[jarich]

There is really only one brand of MVB worth getting and that's the MegaRay. However, MVBs are tricky to get right regarding a good position for heat vs UV exposure. If you buy the HO T5 fluorescent tubes it also will last a year before needing to be replaced, unlike the older style T8s that have to be replaced every 6 months. Having just one light, while convenient for the keeper, is not great for the lizard. Lighting is a complex issue that requires, in my opinion, at the very least two (or more) lights. I'd recommend the T5 for UVB and a PAR 38 halogen flood lamp for basking. Many people will place the fluorescent tube along the ceiling towards the front as this hides the light from being seen outside the enclosure. Then the basking light can be mounted right next to it

 

[Toni17]

Thanks for confusing me some more regarding the lights. The glass doors on the soon-to-be converted TV stand are tinted.

 

[jarich]

Hahaha, sorry didnt mean to make it worse. Basically, put the fluorescent light and the basking light all the way to one side of the enclosure, from the ceiling. They should be as close together as safety allows (the basking light will get hot, so dont put it so close to the other light that it melts it) The fluorescent light should then run about 2/3 of the length of the enclosure. Is that easier or less confusing?

 

[Toni17]

Only 2/3 of the tank? ok. got it.

 

[jarich]

Well you can go 2/3 to 3/4 of the length. You want to give them a part of the enclosure where there is no UV, so that they can get completely out of it should they choose to.