# Is too much UVB bad?



## tofuqueen (Jul 10, 2009)

I have two light clamps in my enclosure. At one end of the enclosure I have a "Repti Glo 5.0 UVB 26W bulb" and at the other end I have a "Sun Glo Basking Spot Lamp Tight Beam 50W" Both are by Exo Terra brand. My Russian Tortoise will be outside for extra exercise and play every day. Right now we're working on some sort of outdoor enclosure for him, but until that's finished, we'll be outside with him for supervised play! So my questions are: Do you think the light set up I'm using indoors is good? Can a tort get "too much" UVB by having the lamp on for 12 hours a day, plus being outside for a few hours each day? Once again, thanks everyone for the help!


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## Maggie Cummings (Jul 10, 2009)

If he's outside for 20 to 30 minutes a day he doesn't need any UVB light. I don't know if too much is bad, but it certainly is unnecessary...


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## Seiryu (Jul 10, 2009)

It depends on a lot of things. Not all tortoises or any reptile, stay in the sun the same amount. Redfoots for instance like it shadier with a little light. Desert species of tortoises are used to being in the harsh sun and used to the high intense UVB and there is NO WAY the UVB lights being on for 8-12 hours are going to come close to simulating how much is given off from the sun.

If you're talking about UVB from the reptile lights. I would not do more than 8-12hours a day of that stuff. And not because of the UVB, but the UVA. The UVA penetrates deeper and usually causes more issues. Most of the UVB lights don't have as good of a ratio as the sun does. 

If you have him in his cage and know you are taking him outside that day, then I agree with Maggie and you technically won't need the UVB lights that day. Although I wouldn't go less than maybe 2 hours of natural sunlight a day.

I have a couple Basilisk, that I take outside on a somewhat regular basis (sometimes they just don't cooperate). Usually for 1-2 hours each, and I put them back in their enclosure WITH the UVB lights on still. I get them vet checked regularly and no issues or anything whatsoever. I've had them as babies for 3 years now.

Most reptiles know how much sun they need. I really wouldn't worry about overdoing it. People leave their tortoises outside 24/7 getting 5+ hours of sun a day I bet. And having a UVB light on for 12 hours won't even simulate that much.

Sorry was a long read.


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## Madkins007 (Jul 10, 2009)

This is really a much more complicated question than it sounds like. As you know, the main reason we use UVB lighting is to help stimulate vitamin D3 production in the skin. So...

1. Is there a risk in too much D3? YES. Too much D3 causes skin problems that looks like sunburns and other medical issues. It is possible to die from an overdose of D3. This is a BIG reason most of us do not like D3-enriched foods- too easy to OD on it.

2. Can you OD on D3 from the sun? NO. While too much sun has other problems (heat exhaustion, sunburn, dehydration, etc.) you will not OD on D3 from it- there is a built-in protection system for that. 

3. Can the UVB from the sun harm you? YES- eye and skin damage is possible, so make sure there is some DEEP shade available at all times, like a shelter with a solid roof.

4. Can you OD on D3 from a UVB bulb? UNKNOWN, but it does not look like it.

5. Is there a risk of too much UVB from a bulb? YES, just like from the sun, but many UVB bulbs put out a different ratio of light than the sun does, so it can be either better or worse.

My recommendation is to gear the bulb and exposure to the animal. The closer to the equator- the more and longer the UVB exposure; the more north or south, the less. Then, look at lifestyle- the more hidden or forest-dwelling, less. The more open or desert, more.

Russians fall neatly into the 'don't need much', so I'd only do about an hour a day. The best guesses I can find suggest that 15 minutes in the sun twice a week is enough.


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## DoctorCosmonaut (Jul 12, 2009)

check out this thread on UVB in "debatable topics" = http://tortoiseforum.org/thread-5893.html


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## tofuqueen (Jul 13, 2009)

Thanks everyone! I've looked into the thread posted above. Lots of great info!

Sonja 
(& Pablo!)


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## DoctorCosmonaut (Jul 14, 2009)

Madkins007 said:


> This is really a much more complicated question than it sounds like. As you know, the main reason we use UVB lighting is to help stimulate vitamin D3 production in the skin. So...
> 
> 1. Is there a risk in too much D3? YES. Too much D3 causes skin problems that looks like sunburns and other medical issues. It is possible to die from an overdose of D3. This is a BIG reason most of us do not like D3-enriched foods- too easy to OD on it.
> 
> ...



I wouldn't say that latitude thing is necessarily correct considering that South American torts live right on the equator, but live mostly under bursh and in jungles/rain forests... I think it has more to do with natural environment, forest vs desert.


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## Madkins007 (Jul 15, 2009)

DoctorCosmonaut said:


> Madkins007 said:
> 
> 
> > My recommendation is to gear the bulb and exposure to the animal. The closer to the equator- the more and longer the UVB exposure; the more north or south, the less. Then, look at lifestyle- the more hidden or forest-dwelling, less. The more open or desert, more.
> ...



Hence the second part of the statement- "Then, look at lifestyle..."

Although, the Chaco Tortoise is quite a bit south of the Equator, and so are many Red-foots. Even at the Big E, a lot of Red-foots live in relatively open places as adults.

UVB decreases steadily as one moves from the Equator- to the point that as you approach the border between the US and Canada, a human will not get enough UVB in the daytime in the winter. This is all well-documented in the UK website http://www.uvguide.co.uk/index.htm.

Offering a Russian Tortoise the same UVB levels as a Leopard Tortoise could* be risky- the Russian in the wild is only getting a fraction of what the African species is getting. (And I say COULD because I don't know of any studies that proves or disproves this.)


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## spring pace (Jul 16, 2009)

i have concerns that when the tort is inside, there is no cool spot for him w/ lights being on either end of the tort table and they both give off heat. smiles, spring


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## tortoisenerd (Jul 16, 2009)

Yes, the temperature gradient is another concern. Great point!


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## tofuqueen (Jul 17, 2009)

Both lights are now at the same end. I have another thread going asking people to critique the enclosure, and keeping the lights at the same end was recommended. Now the hot end is around 92 degrees and the cool end is around 73 or so. Thanks!


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## spring pace (Jul 17, 2009)

good change up sonja, your tort will definitely benefit. smiles, spring


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