Reptile & Amphibian Forums

How much UVB is enough?

I was wondering if there were any studies on how much UVB a bearded dragon actually needed? I don't think I ever saw an exact amount stated or are we all just winging it? I remember that I was told that I needed at least a 5.0 tube but for the life of me, I can't remember why I accepted that as fact.

Here is something to think about...

There is never enough. The sun gives off an unlimited non-reproducable amount of UV rays that reptiles have evolved to use and depend on. The more the better, but there should not be an "enough mark", as "enough" should be natural sunlight everyday for the amount it is out. Nature sets the standards.

Just a thought.
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CANADIAN CHAMELEONS

I tend to disagree. UVB is measureable. The amount of UVB that is sufficent can be measured by blood tests. What I am looking for is if anyone has done studies to determine how much or little is enough. It is already known that too much UVB is bad, as well as too little. For most people too much isn't a problem since their lights only produce a fraction of the UVB that would be put out by the sun. There are however, I am told lamps that will produce several times the amount of UVB the sun produces, making it more important to know proper levels.

To my knowledge no extensive research has been done to determine the minimum or maximum UVB rays a bearded dragon needs daily inorder to properly synthesize vitamine D3 and thus use calcium injested in food. However, natural unfiltered sunlight does produce much more than any UVB producing bulb available to the public for reptile care. The Mercury vapour bulbs put out much more UVB rays much further than florescent tubes, as much as 10 times the amount.

That being said, I have come across various articles about the importance of UVB rays in the daily lifes of reptiles. Might find them an interesting read. Just want to add one more thing before I put in the links. In the wild, most reptiles are not out and about in the full heat of the day in direct sunlight when the UVB rays are at their highest output. Most reptiles instinctively know when to get out of direct sunlight (either through the heat sensing organ at the top of their heads, or other means) and move to a more shaded area or return to a cooler borrow, crevice etc.

www.hagen.com/usa/birds/info_sheet.cfm?CAT=8&INFO=16

www.reptilerooms.com/Sections+index-req-viewarticle-artid-55.html

www.martinsreptiles.co.uk/ukchams/uvlightingresearch.htm

www.beautifuldragons.com

The last website has a section that shows the various UVB outage at different distances from the basking spot and age of bulb. Thought it would at least be interesting in that aspect. Other websites may turn up by doing a google search on importance of UVB for reptiles or similar search criteria.
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PHLdyPayne

I have come to that conclusion as well. I did find a really good site http://www.uvguide.co.uk/index.htm it has a lot of information about lights and UVB.

I love that site. It confirms that unless the animal is within 4 inches or less of any MV bulb, that it could still not get more UV (That could harm it) than they would get in the shade in the wild.

Switching over, wont be so worrysome at all.
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CANADIAN CHAMELEONS

If I read the same site it showed several MV lamps at much higher UVB levels than nature provided for an entire day at different ranges. Just my opinion but I would shoot for a level closer to 9 am and 4 pm. The reason being that most bearded dragons are most active during the mornings and late afternoons. They tend to hide during the hottest parts of the day. Since our dragons don't have the same enviroment and choices as in the wild an average for the area the animal comes from would seem to be reasonable. I am talking about UVB not UV light so maybe I misunderstood.

Yes, but I beleive it showed that it only passed the natural sunlight if you were within 4-6 inches of the lamp.
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CANADIAN CHAMELEONS

Yes but it also doesn't show an average level of sunlight during the time beardies are mostly active. If we try to use the period of most sunlight rather that an average we could be over dosing. Not much danger with most lights but still something to be concerned about. Something like a Cham would be more at risk than a beardie I would think.