UVB lights - help?

[Pushkin]

Hi all! I have a UVB tube light in a hood that I put on top of the screen of my beardie's tank. I'm new to reptiles, and the person I got my beardie from did not even have a UVB light, so I'm kind of in the dark! (no pun intended). I've noticed that a lot of people have their lights mounted inside the tank. Is there any problem with having it on top of the screen, as I do now?

 

[Taterbug]

What tube do you have? The T8 should be mounted inside, if you have a T5 in a reflector hood it may be ok on the screen. Screen can filter the UVB by 30-50% depending on the type if screen you have.
If you can hang it inside, from above you'll give your dragon the best access to the UVB.

 

[Pushkin]

Thanks so much for replying!
This is the light bulb that I bought at Petsmart:

http://www.petsmart.com/gsi/webstor...ferralID=788449dd-cb23-11e3-87fe-001b2166c2c0

and this is the hood that I have it in:

http://www.petsmart.com/supplies/light-fixtures/zoo-med-trade-reptisun-trade-reptile-terrarium-hood-zid36-5142800/cat-36-catid-500037?_t=pfm%3Dsearch

I have it sitting on top of the screen that came with my 40 gallon tank. Because it's a reflective hood, I don't think I can mount it inside - but I'm not sure if I should replace it with a different fixture or not? Also, how do you make sure that it's not a burn risk if you put it inside the tank?

 

[Taterbug]

My phone won't let me see the bulb you got, but some of the folks here have some clever solutions for mounting them inside the cage. You might be able to suspend it with wire, zip ties, command hooks or special "hangers" depending on what tank you have. I don't have experience putting them inside, but see if you can before considering an alternative fixture. The reflectors are helpful at improving the output if the light.

You want to keep a minimum distance from the light of 6" for safety. The bulbs can be harmful up close, but they are actually sort of cool to the touch. (Assuming you have a t8)

 

[CooperDragon]

A 40g tank isn't that big and your fixture is a good one. I'd imagine it would be OK sitting on top even with the screen because of the reflector but I'd make sure to have a high output bulb for it. Is it sitting about 12'' from the basking spot? I don't have any experience with the All Living Things Tropical UVB but my thought is to replace it with a high output Arcadia or a ReptiSun 10.0 bulb.

 

[timisimaginary]

according to that link, the bulb only emits 25 uW/cm2 (though it doesn't say at what distance). that's not nearly enough UVB for a beardie. better levels would be about 100uW/cm2 (constant exposure) or periodic exposure up to 300uW/cm2 on the basking site. also, sitting on top of the screen, even that small amount of UVB is mostly getting filtered out.

if you want to have the fixture on top of the screen, you should probably go with a Reptisun 10.0 T5 HO bulb. the HO bulb will ensure that adequate UVB is making it through the screen top. i'm not sure but i think that fixture you posted is a T8 fixture so you would need a different fixture for the T5 bulb. assuming standard 40G dimensions (36x18x18) you would probably be looking for a 24" long bulb, that would allow some space at the non-basking end with lower UVB levels so the dragon can photoregulate (also include some hides so he can escape the UVB altogether if he wants).

 

[Pushkin]

Thank you so much for your replies!

I just realized that the link for the bulb is not actually correct - that is actually the tropical version, I bought the desert version, which is stronger:
http://www.petsmart.com/reptile/bulbs-lamps/all-living-things-desert-fluorescent-uvb-bulb-zid36-14771/cat-36-catid-500036?var_id=36-14771&_t=pfm%3Dcategory

But I am definitely going to look into the Reptisun 10.0 - I keep seeing that everywhere, it seems to be the one to get. They didn't have it at my local Petsmart, so I got what they had, but I'll look at replacing it!

 

[Taterbug]

Thank you so much for your replies!

I just realized that the link for the bulb is not actually correct - that is actually the tropical version, I bought the desert version, which is stronger:
http://www.petsmart.com/reptile/bulbs-lamps/all-living-things-desert-fluorescent-uvb-bulb-zid36-14771/cat-36-catid-500036?var_id=36-14771&_t=pfm%3Dcategory

But I am definitely going to look into the Reptisun 10.0 - I keep seeing that everywhere, it seems to be the one to get. They didn't have it at my local Petsmart, so I got what they had, but I'll look at replacing it!

Check online. I use amazon, and with prime shipping it's the cheapest source I've found for bulbs. http://www.amazon.com/Zoo-Med-ReptiSun%C2%AE-Fluorescent-24-Inch/dp/B0009YHSWK/ref=sr_1_1?ie=UTF8&qid=1398379274&sr=8-1&keywords=reptisun+10.0

 

[jarich]

according to that link, the bulb only emits 25 uW/cm2 (though it doesn't say at what distance). that's not nearly enough UVB for a beardie. better levels would be about 100uW/cm2 (constant exposure) or periodic exposure up to 300uW/cm2 on the basking site. also, sitting on top of the screen, even that small amount of UVB is mostly getting filtered out.

if you want to have the fixture on top of the screen, you should probably go with a Reptisun 10.0 T5 HO bulb. the HO bulb will ensure that adequate UVB is making it through the screen top. i'm not sure but i think that fixture you posted is a T8 fixture so you would need a different fixture for the T5 bulb. assuming standard 40G dimensions (36x18x18) you would probably be looking for a 24" long bulb, that would allow some space at the non-basking end with lower UVB levels so the dragon can photoregulate (also include some hides so he can escape the UVB altogether if he wants).

I would be cautious about suggesting exposures that high, Tim. Anything close to 300 um/cm2 is incredibly high and shouldnt be sustained for any length of time. Since most people keep their UV lights on the whole day, like you said, a reading of around 100 um is great.

 

[timisimaginary]

i just went outside and measured the UVB from my backyard and got a reading of 250uW/cm2. when clouds pass over it gets down to around 100-150uW/cm2. in their natural habitat in the australian outback they can easily see exposure above 300uW/cm2. now, if you're using a tube bulb like the reptisun 10.0, you don't want levels that high throughout the vivarium, for constant terrarium-wide exposure you want to shoot for around 100, but if you're only using an MVB on the basking site, you want briefer periods of more intense exposure allowing the dragon to move on or off his basking site as necessary. 300 may be a little high, since there is obviously variation from day to day in the wild. some days will be cloudy and stay in the 100-150 range, while an exceptionally clear and sunny day can get up to 450uW/cm2 in the outback. so maybe 200-250 is a better range for daily levels, right in the middle. and as always, regardless of UVB source every terrarium should have a gradient as well as one or two hides with 0 UVB exposure.

 

[jarich]

True, but you have to be careful about using readings like you get from sunlight and comparing it to bulbs in an enclosure. (See Steve's website at Solarmeter to look at the comparisons of readings outdoors to indoor lighting.) Also, you have to think about the natural behaviour of the lizards and when they make use of that light. UVB lights, especially fluorescents and MVBs, have a much different spectral output than sunlight. You see a lot of high peaks in the spectra, with very little in between. Its why many people now recommend UVI as a guideline as compared to just um/cm2.

You are obviously doing a good amount of research on this. Have you considered joining the group UVBmeterowners on yahoo? You will find a lot of great research and so many incredible lighting experts. Next level stuff!

 

[timisimaginary]

i have joined that group since i've seen you mention it, but haven't really read much there yet.

i have the solarmeter 6.2 which just displays uW, vs the 6.5 that displays UVI, but UV index is based off uW/cm2 so it's just different ways of expressing the same measurement. i know the two meters have slightly different response curves, but don't know that one is necessarily more "accurate" than another. they're just inaccurate in slightly different ranges. short of using scientific instruments, we just have to accept those inaccuracies and do our best. there are certainly differences between natural light and artificial light throughout the UV spectrum, but these two meters are really designed primarily for measuring one small area of that spectrum, the UVB range that is useful for D3 production in reptiles. neither meter is going to tell you if you have dangerous levels of UVC or insufficient UVA (though there are other meters for that). so you can't really come to any conclusions about the spectral response of artificial vs natural light based on either of those two meters alone outside of that narrow UVB range.

i do wonder about the distance recommendations on some bulbs. for example the mega ray 100W MVB recommends a minimum safe distance of 12". well, at 12" i get around 120-150 uW/cm2, well below natural sunlight values; i don't get near 250 uW until i'm around 6" away. so i wonder if those recommendations are based on some other factor. perhaps UVC exposure is too high at those distances and causes eye problems. or maybe there's enough variability that some bulbs will put out much more UVB at that distance. mine has been in service about 5 months, so should still have plenty of useful life left.

 

[jarich]

It's not so much about one being more accurate than the other, more about how you are measuring and what you are measuring. For instance, you'll find with taking a 6.2 outside in sunlight that the incredibly high UVA will skew your measurements to be higher than they are for just UVB. Basically the sensor isn't really meant to measure UVA, and is so minimally activated by it, that it won't make much difference when you measure say a fluorescent light (poor producers of UVA). However, taking it out into sunlight where the UVA is insanely high, will still have an effect on the sensor and give you false readings. So a reading of 250 um outside is vastly different from a reading of 250 um under your light. Again, if you search that yahoo group for threads on Solarmeter readings, Steve from Solarmeter gives a much better explanation than I do. He explained it all to me about a year ago I think. I'll see if I can track down the link and give it to you. It's a brilliant (and humbling ), experience to see the incredibly vast knowledge of the people on that group and that they take the time to really explain it all is fantastic.