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MV bulb placement and UVB tube light output

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  • Matt Fumich
    This question was posted on the Iguana Den board but it was suggested that I post it here since not everyone here is a member there, I don t think. Since I can
    Message 1 of 3 , Jan 2, 2005
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      This question was posted on the Iguana Den board but it was suggested
      that I post it here since not everyone here is a member there, I don't
      think.

      Since I can set basking temp under a MV bulb by altering the distance
      between the bulb and the perch, temp is not an issue. Is there ANY
      reason for me to be concerned about over exposing my ig to UVB? Do I
      need to adjust the distance or use a filter to REDUCE his UVB exposure?

      As for the UVB output of UVB tube lights, I would expect the reading
      to be listed as a ratio. Kind of like MPH which, mathematically, is
      miles/hour. Since UVB is measured in nm, the readings should be
      presented as nm/(distance in inches). Right now my lights register
      20/12 which is pretty useless. Which lights I replace them with is
      irrelevant as long as they're used at the distance necessary to
      provide sufficient UVB to my ig. Since the distance between the perch
      and UVB lights is typically recommended to be less than 12 inches,
      for this purpose, nm/12 would be logical. A good quality light
      may put out UVB twice as high as what is needed. A lesser light may
      only put out UVB 10% higher than what is needed. It is typically
      recommended that light be replaced when they drop to 70% of the output
      of new. That seems a little ridiculous to me if 70% output is still
      sufficient for your needs. It makes more sense to replace the tubes
      when they no longer have sufficient output. And there in lies the
      question. For an iguana, what is the minimum recommended exposure of
      UVB and how long each day should he have that exposure?

      Personally, I think both questions are best suited for the other board
      but any help would be appreciated.

      Thanks
      Matt
    • Matt Fumich
      Correction. UVB is represented in uM not nm.
      Message 2 of 3 , Jan 2, 2005
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        Correction.

        UVB is represented in uM not nm.
      • bobmac@reptileuv.com
        Hello Matt, ... that I post it here since not everyone here is a member there, I don t think.
        Message 3 of 3 , Jan 3, 2005
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          Hello Matt,

          >This question was posted on the Iguana Den board but it was suggested
          that I post it here since not everyone here is a member there, I don't
          think.<

          The questions you raise here are bit to advanced for the general Ig
          board except for the knowledgeable people that are on both groups.

          I would highly recommend you read as much of the files section as you
          can several times to get a grip on what you are seeking. The "ISS
          article re edited" will answer a lot of your questions and Dr Gehrmann's
          on "Comparison of two artificial light sources" as well will help.

          There are just a very few (almost only one) bulb(s) on the market that
          will give you sufficient UVB after 70% of the decay has expired.

          I'm going to repost Fran's and my conversation from just a short while
          ago to help understand the differences in reptiles needs.

          BM

          Frances Baines.

          Hi, Scott.
          That is a VERY good question. What species do you keep?
          At the moment I'm not aware of any such chart, if there is one, I too
          want to see it!
          I think the general feeling at the moment is that herpetologists-
          including us hobbyists - are actually pioneering this field right
          now.... there is so little known, and blood testing of reptiles to
          check their vitamin D status is still very much an experimental
          phenomenon. Iguana keepers are a little ahead, because I guess the
          creature is so big a blood sample is no big deal, and also MBD has
          been so obvious a problem in this species that it has been researched
          for years.

          So far, various authors are suggesting that the best way to determine
          how much UVB our reptiles need is to research what UVB they would
          likely receive in the wild. This does not mean, find out the noonday
          UVB for that part of the world, and stick it in the vivarium...
          because that would be really unsuitable for shade-dwellers, those
          that live in rainforest canopy and especially, crepuscular species
          who may get little or no UVB in the wild.
          Even desert dwellers often have early morning/late afternoon basking
          habits and since the amount of UVB in sunlight is proportional to the
          height of the sun above the horizon, amongst other things, only the
          most sun-worshipping of reptiles will ever sit in full desert mid-day
          sunshine levels(say 350uW/cm2) and even then, probably those levels
          don't exist for more than a few hours in the middle of the day.

          I've now seen several articles in which authors stress that we must
          now consider providing what might be described as "UVB gradients",
          like heat gradients, whereby our reptiles can move in -and completely
          out- of the UVB and regulate their own UVB basking times. This seems
          a natural enough conclusion! I think maybe (personally speaking) I
          like the idea of providing my bearded dragons with at least one small
          patch of "hot sunshine" around 200-300uW/cm2, since these do bask in
          full sun during the day, in the wild. My dragons do sit in that
          hotspot for small parts of the day; I've noticed they tend to hang
          around longest in the 50-150uW/cm2 zone, though, but I haven't done
          any serious recordings of their behaviour yet....

          I've been trying to find data myself and so far I have found studies
          with data on Chuckwallas, Chameleons and Green Iguanas.

          The Chuckwalla study suggests that Chuckwallas choose to bask in
          areas of high UVB exposure (as high as 383uW/cm2 was noted) for part
          of the day when this is available to them.

          The Chameleon study addresses egg hatchability in Panther Chameleons
          and suggests low levels of UVB (a gradient between 5-15uW/cm2) are
          optimal, however another writer suggests that levels similar to those
          found in the wild chameleon's habitat (a gradient between 50 -
          100uW/cm2) are more suitable. High levels are seen to be harmful.

          Iguanas appear to have requirements - and behaviour patterns -
          somewhere between the two. One author recommends keepers of green
          iguanas to make levels of at least 30-50 uW/cm2 available to their
          animals, and another study indicates that an absolute minimum of
          10uW/cm2 is required at a basking site, and a gradient of 20 -40
          uW/cm2 is optimal; these levels would all be around the minimum
          level a wild iguana would experience during the day, whilst in the
          shade.

          Few snakes or amphibians, or nocturnal/ crepuscular lizards such as
          geckos, are thought to require ultraviolet lighting, at present, and
          authors suggest that dietary vitamin D3 may be adequate for most
          species. However, Diamond Pythons are known to require UVB in
          captivity. Snake eyes appear to be sensitive to too much light, (not
          necessarily just UVB, though) and so as with the other reptiles, they
          must be able to find shelter from light and from UVB if it is used.

          The main articles are:
          1. Aucone B.M., Gehrmann W.H., Ferguson G.W., Chen T.C., and Holick
          M.F. 2003. Comparison of two artificial ultraviolet light sources
          used for Chuckwalla, Sauromalus obesus, husbandry.

          2. Ferguson G.W., Gehrmann W.H., Chen T.C., Dierenfeld E.S., and
          Holick M.F. 2002. Effects of Artificial Ultraviolet Light Exposure on
          Reproductive Success of the Female Panther Chameleon (Furcifer
          pardalis) in Captivity. Zoo Biology 21:525-537

          3. MacCargar, R. Iguanas and Artificial Ultraviolet Light: How and
          How Much Made Simple - Well, Not Exactly Simple. 2003. Journal of the
          International Iguana Society 10 (3) 82. -now fully revised, 2004.

          I'm typing this offline so I can't check, but I *think* these are all
          in the Files section?
          Hope that helps!
          Frances

          Fran,

          This is excellent writing! (Looks like something the Info site should
          pirate) Normal natural habitats UV, the reptiles natural habitats, and
          having an understanding of the amounts of UVB in different shaded areas
          such as the difference between reflective qualities of sand and stones
          as compared to greenery and or water basins would also need examination.
          Some noted information centers constantly bring up the fact that green
          iguanas spend much of their time in the shade during mid day and
          therefore aren't exposed to much UVB. While it definitely is true that
          iguanas as well as most basking reptiles spend the hotter portion on the
          day in the shade, it's also a fact that readings of 50-300uW can be
          registered in the shade (while direct sunlight is at 350-450). It would
          be difficult for this species to be exposed to less then 50uW from 8AM
          to 4PM.

          As you mentioned, few creatures would spend any length of time in the
          higher levels of UVB. And although Gehrmanns study exposed spiny tailed
          iguanas to 380uW to get the OH25 blood serum levels that matched normal
          wild levels, I suspect that 6 hours a day of 250uW/cm2 would have had
          the same results. Remember the chucks were chosen because they would be
          a good cross example of desert reptile species.

          Chameleons are a difficult species for me personally to figure out and I
          have had to change my standing on UVB recommendations. Gary Fergusons
          teams work indicates that chams (panther species at least) are best at
          about 10microwatts. In the wild it is logical to realize that chams
          would be exposed to much higher levels of UVB at least part of the time.
          Readings here in NC USA have shown that even in the deepest bushes when
          there is 250uW in the sun, it's very difficult to get readings under
          10uW. When its 350-400uW in the sun it becomes even more difficult to
          get low numbers such as 10-20uW.

          Just how often is it a bright sunny day in the chameleon species in
          question natural setting though? Rain fall in Madagascar, where the
          Panther chams originate, varies from tropical rain forest to desert
          conditions. The east coast of the country can get up to 118 inches
          (3000mm) a year. There are free ranging breeding colonies of Jackson
          chams in S Florida and Hawaii where it doesn't get any where near as
          much rain or cloud cover. I have seen many pictures of chameleon
          breeders in Florida and Arizona using outside habitats, and it's easy to
          see that these creatures are exposed to much higher then 10uW at least
          some of the day.

          I have heard of many chams that were not doing well under low level UVB
          (10uW) and had complete turn a rounds when given the ability to be
          exposed to up to 50uW (with UVB gradient off to 0uW). Keepers have sent
          me pictures of the results. To contradict this I have also heard of
          chameleons have physiological problems due to the higher UVB exposure
          such as from your friend Rob. I personally have seen conjunctivitis in
          chams exposed to higher numbers, 75-100uW. Neither the good results nor
          the bad results can be ignored.

          To err on the side of safety would seem the logical choice. Unless there
          is a reason to increase the levels of UVB for a cham not "doing well"
          under traditional UV tube lighting, the lower numbers such as 10uW to
          possibly 30uW with gradients to 0uW would be my suggestion at this time.

          Speaking of "UVB Gradients", in my rehabilitation (iguanas) work I find
          the observation that creatures that have been UVB starved will spend
          almost all of the 12 hours of light directly under the Mega-Ray flood.
          (I just had three iguanas come from out of state over the last three
          months that fit this category well) These lamps all produce 150-250 (or
          higher depending on the condition of MBD) at the basking area meaning
          that the animals are exposed to 150-250 microwatts for most of 12 hours
          only spending time away from the UV during feeding and looking for ways
          to get out. My family creatures that have had great UVB for years will,
          as you said, will be on the outside of the UV circle under 75-150uW.
          This is how I came up with my recommendation of these numbers of 75-150
          microwatts for most basking UVB dependent reptiles.

          In the end I believe that we will be able to group species and UVB
          recommendations even to the point of a few microwatts for a few minutes
          for your crepuscular species such as the gecko species. I really love
          that study.


          As a side point. You mentioned that mid day readings of "350". The high
          readings can be as high as 450uW. Here in NC USA, I get readings over
          400 during the summer months and as little as 75uW/cm2 in the winter
          with bright sun shine. This is with the US standard of measurement. The
          European's measure the UVB spectrum at a bit of a lower number stopping
          at 315nanometers instead of 320nanometers. The closer to the equator,
          the less variance in UVB readings during the seasons as well.

          Unfortunately Fran, I feel that only dedicated herpetologist and
          hobbyist will ever look for these findings in fine tuning their
          husbandry.

          I am hoping that with your and Dominick's writing skills, this kind of
          information can be posted on the Info site as a reference that all can
          access.

          Best to all,

          Bobmac
          www.reptileuvinfo.com

          * .


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