How important are domes?

[Strange_Evil]

I have a clamp fixture but no dome for it. So the bulb is out. It's a power sun mercury vapor bulb, will i need a dome? Will this shorting its burn life(uv output) or am i good to go?

 

[jdpFL]

I would think that without a dome, the bulb would just scatter the uv and light and heat all over, and not focused on your enclosure or on your tegu. Which would definitely make it less effective. We used a laser thermometer and found a major difference between spot lights and regular bulbs, even of the same wattage, that was with a dome.
Maybe you can get a broken lamp at a thrift store and use the dome from it....our something like that, to save money.

 

[katoeLAZARO]

You can always get a cheap one at homedepo

 

[james.w]

I don't use domes on any of my bulbs.

 

[Strange_Evil]

Good to know,thanks guys, i already have all set up and without a dome my temps are fine, cool side is 84f basking spot is 110-113f, near the basking spot is in the 90s.

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And i am pretty sure all know i am a horrible craftsman. This is my first real build, it's 4x3x2. My bottom is a bit to large, i made the frame slanted and glass fits messed up. I worked hard on it and i'm glad i built this, i know have a pretty good idea what it takes to make a cage, so when i do build my permanent enclosure it should look much better and go smoother.

 

[laurarfl]

The dome definitely improves the UVB concentration. I just put a quick link that states the dome improves UVB by 100%. http://exo-terra.com/en/products/light_dome.php. You can get a cheap one at Home Depot, just make sure you get a ceramic fixture with a Mercury Vapor Bulb.

I also have enclosures with ceramic fixtures in the ceilings, so they don't have domes. And then I have cages that have fixtures w domes.

 

[herpgirl2510]

I use domes with all my powersuns however with basking bulbs I do not.

 

[laurarfl]

Just to clarify, i use domes with PowerSuns in tanks, etcs. The larger enclosures that already have fixtures cannot accomodate a dome. Otherwise I would use domes so that the beam is more focused, like jdpFL indicated.

 

[herpgirl2510]

I had originally had my powersun in just a ceramic fixture but I was told it would not be close enough since it was aout 30" overhead. I was thinking if I did not use the dome the light would disperse more and that would be good since my guys are large and share a basking area.

 

[james.w]

Laura, your link is no good.

I found the page you were referring to and I'm gonna guess that is just marketing nonsense to try and sell their product. UVB diminishes the farther it travels, therefore if it is reflecting off of the dome it would be less effective. The dome may help to localize the light/UVB but I doubt it makes the bulb provide more.

If someone out there with a solar meter would like to do a little test I'm sure we would all like to see the results.

 

[jdpFL]

Herpgirl that makes sense to me, if you need your light to cover a larger area. We have adjusted the height of our clamp lamps for the same reason, but the further away you get, the less concentrated the light and heat, so we switched to spots for heat. For the sav anyway, since he needs that ridiculously hot basking temp.

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Interesting study. And scroll down to see what a dome does to measurements...
UV Lighting for Reptiles: A new problem with high UVB output fluorescent compact lamps and tubes?
http://www.uvguide.co.uk/phototherapyphosphor-tests.htm#reflectors

 

[laurarfl]

"The use of a reflector can produce a remarkable increase in UVB output at a basking spot. Even a piece of ordinary aluminium foil placed behind a fluorescent tube will significantly improve its performance, but if a reflector, such as the inexpensive clip-on type used for aquarium lighting, is fitted to a UVB tube it is possible to virtually double the output of the tube. The reflector effectively gathers a large percentage of the UV light from the sides and back of the tube, which would otherwise be absorbed by the walls of the vivarium, and redirects this forward into the enclosure."

http://www.uvguide.co.uk/fluorescenttubereflectortests.htm

http://www.uvguide.co.uk/lightingsurveyintro.htm

The info with MVB and domes is not available right now on uv guide website because the test results are being reposted with new data. But these other links are the best test results out there. Reflection does not cause UVB to dimish or there wouldn't be medical conditions such as photokeratoconjunctivits which result in "snow blindness" when UVB reflects off of snow or other bright surfaces, or the increase in cataracts in people who live in areas with a lot of water and who spend a lot of time engaged in water sports/boating. I'm sure the ExoTerra website took some liberties and generalized with their "increases UVB output by 100%" statement, but a dome will not reduce UVB output. Think of the rays going downward, then reflecting the sideways rays so that they, too are focused downward. It's not that NOT using a dome is wrong or bad, but using one with a reflective surface WILL increase the UVB reaching the basking spot below.

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"An even more powerful increase is seen if an aluminium dome reflector is used. We first investigated the effect of placing compact lamps in dome reflectors of different types in 2005. Our first tests showed that the output was more than six times greater beneath a compact lamp, if either a polished aluminium or a brushed aluminium dome reflector was fitted. Obviously, an increase of that magnitude with a lamp that was already emitting very high levels of UVB could be dangerous."

http://www.uvguide.co.uk/phototherapyphosphor-tests.htm#reflectors

http://www.coursencoating.com/uv_reflectormirror.htm

http://www.uvguide.co.uk/fluorescenttubemeshtests.htm

http://blog.cureuv.com/?p=1424

http://www.exotic-pets.co.uk/uv-tube-reflectors-for-sale.html

http://www.sanuvox.com/catalogue/Sanuvox%20UV%20CoilClean%20Series.pdf

http://www.ultravioletsystems.com/pdf/SharpSaw_Article_MJ_02.pdf even wood curing systems use reflectors to increase UV

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No, it doesn't make the bulb provide more, it gets the most out of the bulb you are using (provided you need a good amount of UVB) and prolongs the life of the MVB.

 

[Strange_Evil]

Thank you for all the helpful info and great links, i was using the wrong type of fixture, i just realized its not ceramic but it was rated for 200watts so i thought i could use. Long story short i stopped being lazy and mounted a fixture inside zoo med deep dome, temps are perfect.