UVB

From UroWiki

Jump to: navigation, search

Contents

What is it?

UVB stands for "Ultraviolet light, type B" and is medium wavelength (280–320 nanometers) ultraviolet light. Although UVB itself are measured by its nanometer output, its useful output is measured in µW (microwatts). It is normally emitted by the sun, can cause sunburn and has been linked with cancer.

Why do reptiles need it?

Due to lack of natural UVB in a typical enclosure - the UVB content in direct sunlight is filtered out by normal window glass - captive uromastyx are unable to synthesize sufficient amounts of vitamin D3. Owners need to provide an artificial substitute for this natural source, in the form of UVB bulbs (keepers can of course sprinkle the uromastyx' food with vitamin supplements, but these are shown to be less effective than full-spectrum lighting). These come in several varieties and are dealt with below. UVB must be provided across several photogradient zones, as well as all year round (regardless of photoperiod).

Types of UVB-emitting bulbs

UVB strip lights

Pros:

  • Work well
  • Easy to use and incorporate into your enclosure
  • Easy to find and purchase

Cons:

  • Not cheap compared to normal lightbulbs
  • Need to be replaced every six months to continue to provide adequate UVB, thereby adding even more to their cost
  • Do not produce any measurable heat, thus necessitating the use of auxiliary heat
  • Generally need to be within 30cm/12" of the lizard for it to gain full benefit
  • Some may not be in the correct wavelength for vitamin D3 synthesis
  • Some may degrade very quickly
  • Some may be too weak for any sun-worshipper, even when new
  • Some may be too strong and cause blindness through unnatural UVI levels and short wavelength UVB (fixture/reflector can be a factor)
  • Some may emit UVC, which kills all living cells
  • The animal may be fooled by the low lux and look directly into the bulbs, causing health concerns

Note: there are a few better tubes, but they are usually made in Germany; you can check this information from the packaging.

Compact fluorescent (CF) lamps

There have been many studies indicating that compact fluorescent lamps can be dangerous to your lizard's eyesight, and as such should not be used. You can read the research here and here.[clarification needed]

There are also some great concerns with some coil and tube fluorescent UVB-producing bulbs. Many are made very cheaply in China and there is no to little quality control and some of these fluorecents can be very dangerous. There are a few "safer" fluorescents, however these are usually still made in Germany and 90% of the pet shops in North America carry Chinese-built fluorescents.

  • Some may not be in the correct wavelength for vitamin D3 synthesis
  • Some may degrade very quickly
  • Some may be too weak for any sun-worshipper, even when new
  • Some may be too strong and cause blindness through unnatural UVI levels and short wavelength UVB (fixture/reflector can be a factor)
  • Some may emit UVC, which kills all living cells
  • The animal may be fooled by the low lux and look directly into the bulbs, causing health concerns

Mercury vapor bulbs (MVB)

Mercury Vapor Bulbs provide (in most instances) heat as well as UVB/UVA. These bulbs last longer then typical tube style UVB bulbs do. In general, a good MVB (such as the Mega Ray) should last approximately one year or longer with sufficient UVB output. For the most part, replacement every year is recommended unless you have UVB/UVI meters. Some bulbs have been known to output sufficient UVB much longer, but must not be lowered closer to the basking platform so close that the Uro could be burned.

Self-ballasted (SB) MVB bulbs are the most common, and produce heat as well as UVB/UVA.

External-ballasted (EB) MVB bulbs are also common, although not as widely used by the 'average' keeper. These bulbs emit UVB/UVA only. They emit very little heat and need to be used in combination with other basking bulbs. If at all possible, you should provide a secondray basking spot without or with much less UV, so that the animal can move in and out of the UV light at will depending on how much D3 is in its body.

Alternative sources of UVB

The best source of UVB is, of course, unfiltered sunlight. However, if you are going to have your uromastyx receive direct sunlight (in an open enclosure outside, for example), you must make sure of the following:

  • It is in an enclosed area that it can't escape from
  • It has enough room to run and move around
  • It is protected from predators
  • It still has a selection of cool, shaded places to hide
  • The unfiltered element is important - this means direct sunlight! Any type of glass will filter the useful UVB out of the sunlight.
  • Thermometers should be used inside the outdoor enclosure
  • Watch for signs of stress when bringing your uromastyx outside and if they are stressed (prolonged constant hiding) bring them inside to their home. Stay away from the enclosure but keep a watchful eye.
  • If bringing your uromastyx outside, put it in a safe box before bringing it outside, place the box in the outdoor enclosure and secure it. Uromastyx when encountering real sunlight will try and run and they can move surprisingly quickly when at PBT (preferred body temperature).

Even taking all of this into account, it is recognised that natural sunlight is not available all year round, or in all weather conditions. A UVB-producing bulb should therefore always be available inside the permanent enclosure.

Controversy with other bulbs

A UVB meters owners' group[clarification needed] tested a new Zoo Med 100W PowerSun and it had a UV index of 20 at a distance of about 30cm (12"), which is about twice the recommended rate at any basking spot. Apparently, the phosphor coating had been thinned (presumably in a cost-cutting measure or to compete with competitors) making it very uneven, with some bulbs even having small holes in this phosphor layer; this allowed high radiation spikes through the coating. It is not currently known if the 160W model suffers from this same manufacturing flaw, but for health reasons it is currently recommended to avoid this brand of bulb.

It is, of course, always best to check the UV output yourself if possible, with UV/solar meters. There are also many other bulbs to avoid, and the Zoo-Med PowerSun range are definitely not the worst on the market. However, ReptileUV.com's Mega Ray is the recommended bulb for any sun-worshipping basking lizard, and other bulbs should be avoided unless UVI/UVB meters are used. A UV meter that can tell wavelength should be considered, although the cost is high and may not be a feasible purchase for the average keeper.

Faulty bulb recalls

There have been a number of recalls and faulty bulb warnings at the end of 2009 and the beginning of 2010, largely centering around those made by Westron of Canada (as outlined in an analysis by UVGuide.co.uk), which have affected the T-Rex Active UV/Heat Bulbs, as well as the popular Mega Ray MVB.

Personal tools