Indoor UVB Lighting for Tortoises
- stars & other small, dryish area species -
T-5 HO fluorescent UVB lamps for reptiles by Zoo Med and Arcadia (2012).
Best UV for tortoises
The best UVB source is the sun! An outside enclosure is a must for tortoises, even if they can only use it part time. For adult tortoises, build the pen as large as your space allows. The bigger the enclosure, the better. In addition to the necessary UVB exposure, outdoor "exercise" (walking, climbing, etc.) is immensely important to tortoises' well-being. Let your tortoise roam outdoors as much as possible, weather permitting.
If you live in a warm climate and your tortoise spends most of his days outside with free access to the sun, you won't need to use UVB bulbs. Cost of UVB = $0.
On the other hand, if you live in a cooler climate with a very short outdoor season, it's important to use reptile UVB lights indoors in addition to non-UVB basking bulbs and heaters.
When purchasing UVB lights, always buy good quality reptile specific bulbs from trusted manufacturers like Zoo Med and Arcadia.
Cheap, copycat bulbs of unknown brands can emit dangerous UV radiation, for example, a too high level, the wrong wave length, or the wrong type. Tortoises need UVA and UVB, but not UVC which is harmful to them.
It's best to buy UL listed and prewired reptile lighting and heating products. Any DIY electrical wiring can be a fire hazard. Unless, you are an electrician and know what you are doing. :O)
b.) Follow manufacturer's instructions
Always attach lighting and heating devices securely and according to the manufacturer's directions. Improperly installed tortoise enclosure fixtures that have become loose and fallen off have caused many house fires.
Also, do check the minimum installation height for your specific UVB lamp and the recommended Ferguson UVB zone (see UV readings page) for your species.
c.) Lamp stands
Zoo Med reptile lamp stands work well with most dome type light fixtures. They are adjustable in height and depth and allow you to position lights exactly where you want them. They come in two sizes. I like the bigger stand, model LF-20, better because it has a larger foot that makes it more stable.
d.) Caution with clamps
Avoid attaching light fixtures by their clamps. Clamp fixtures can slide down to one side, or even fall off, and start a fire. Using a reptile lamp stand and a bulb fixture that has a metal hanging loop is a safer way to install lights. If you have to use clamps, try double securing them with welding ground clamps (pic). Welding clamps have a very strong grip, but other heavy duty steel spring clamps work as well.
e.) Hooks & brackets
UVB and heat lamps can also be installed securely by suspending them from sturdy ceiling hooks or wall brackets. Light fixtures that have built-in hangers, for example, domes with metal loops on the top, are easiest to use. Lamps should not be hung by their cords.
f.) Smoke alarms
Keep hot bulbs away from any flammable materials like enclosure covers or nearby curtains. Do install smoke alarms in your tortoise room, garage, basement, or where ever you keep your heated indoor enclosures.
UVB & basking
Tortoises need access to UVB and hot basking areas to stay healthy. The UV output of reptile bulbs varies. Some of them provide both UVA and UVB, while others only supply UVA. Check the box labels.
Indoors, you can provide UVB with long reptile fluorescent tubes, reptile mercury vapor bulbs (MVB's), or the new reptile metal halide UVB lamps.
Just like the basking area, the UVB area should be a large zone from the most to least intense. UVB should be at the max under, or right next to, the basking bulb and then taper of to nothing over a large area. The whole body of the tortoise should be warmed and under the UVB light, not just a small spot on the top. The other end of the enclosure should ALWAYS provide a shaded, no UVB, area for the tortoise to retreat to as needed.
Long reptile UVB fluorescent tube sizes. T-12 is the oldest size, T-8 was the common size before the new T-5 HO tubes were released. Reptile T-5 HO tubes are stronger and put out twice the light and UVB of the older the T-8 tubes.
Long T-8 UVB tubes (old style)
Zoo Med's ReptiSun fluorescent UVB tubes have been popular for years. They are available as 2.0 UVB, 5.0 UVB, and 10.0 UVB bulbs. For Star tortoises, the 10.0 bulb is better than the weaker 5.0.
Many tortoise keepers are switching from the older T-8 tubes to the newer, stronger T-5 UVB tubes, especially in larger enclosures. Due to their higher UVB output, T-5 tubes can be installed higher above the tortoise.
Long T-5 UVB tubes (new style)
Two brands of the new T-5 HO (high output) UVB tubes for reptiles are available in the U.S. - Zoo Med and Arcadia. Both used to made in the same factory in Germany and were of comparable quality, but after Zoo Med's manufacturing change, the Arcadia T-5 tubes are now considered to be the better ones putting out more UVB.
These T-5 HO UV tubes will not fit in the old style T-8 fixtures. They require T-5 specific fixtures.
1.) Arcadia T-5 tubes (update winter 2011-2012)
- In the winter 2011-12, the new "D3+ Reptile T-5 Lamp" fluorescent tubes from Arcadia Products Plc, U.K., became available in the U.S. on a limited basis. These linear reptile tubes produce a high amount of visible light, UVA (30%), and UVB (12% desert, 6% forest). The light color looks natural, and the bulb is flicker free. Use the desert species 12% UVB bulb for Star tortoises.
- According to the manufacturer, the Arcadia D3+ T-5 desert species tubes (12% UVB) provide 100% more visible light and 95% more UVB than reptile T-8 tubes of the same length.
- The Arcadia D3+ T-5 desert species tube is available in several lengths. These D3+ T-5 tubes should be used with T-5 fluorescent reflector fixtures.
- Zoo Med started advertising their new ReptiSun T-5 HO UVB tubes for reptiles in Nov 2012, and they became available for purchase soon after that. Previous T-5 bulbs from Zoo Med were not specifically for reptiles.
- T-5 HO ReptiSuns are available in 5.0 and 10.0 UVB strengths and in several lengths. Matching T-5 HO terrarium light fixtures, aka terrarium hoods, are for sale as well.
- The recommended installations heights for the Zoo Med T-5 HO UVB tubes are 12"-24" above the animal for the 5.0 tubes and 18"-36" for the 10.0 tubes. Check the info on the box.
- Zoo Med announced their new reptile LED & UV terrarium fixtures in spring 2014.
- They are available in two versions: LED only and LED with UVB tubes.
- Hood model that combines Zoo Med's ReptiSun T-5 HO UVB tubes with LED lights is called the "ReptiSun LED UVB Terrarium Hood". They are available in several lengths.
- Little info available about using LED's in tortoise setups. Many keepers are staying away from LED's until more is known about them.
UVB tube fixtures & reflectors
Shop light and strip light fixtures are perfect holders for the long UVB fluorescent bulbs. Always check the size info to see if the fixture is made for the older T-8 tubes or the current T-5 HO tubes.
Using reflectors with the UVB bulb fixtures maximizes the light and UVB output by directing it all into the enclosure. Always check the minimum installation distance on the box to keep the UVB at a safe level for your tortoise. Ideally, use a UVI meter as well to create the appropriate Ferguson UVB zone for your species.
Compact (short) UVB bulbs
Compact reptile UVB bulbs are short fluorescent bulbs that usually, but not always, screw in just like regular light bulbs. They can be straight or coiled (spiral) in shape. For tortoises, long UVB tubes are preferred over these compacts.
Compact UVB bulbs have created a lot of controversy among tortoise hobbyists. Some keepers say there are fine to use when properly installed overhead, while others swear compact bulbs have caused severe eye problems, even blindness, to their tortoises.
a.) Compacts - possible eye damage
- Some years ago, several reptile keepers reported eye problems in their animals due to the very intense UV radiation from some compact fluorescent bulbs at short distances. These bulbs have now been replaced with new, improved designs. Read the 2007 special report [offsite] by UV Guide UK.
b.) Compacts - small UVB zones
- Even the best quality compact fluorescent UVB bulbs are NOT ideal for tortoises because they cannot provide large enough UVB zones at sufficient intensity. The UVB gradient is intense: too strong and possible harmful at close distance and too weak at a usable distance. (Source: Dr Baines, UVB Meter Owners group)
c.) Compacts - possible initial UV spikes
- Compact fluorescent bulbs, especially older models, can have an initial burn-in period when the UVB output is higher than normal. For example, with the older Zoo Med compact bulbs the period of high light and UVB output lasted about 150 hours. During that time, it was best to place the bulb higher than usual or to preburn it away from the tortoise enclosure.
d.) Compacts - placement
- Compact fluorescent bulbs, like all UVB lights, should not be used bare but be installed in a light fixture and placed DIRECTLY OVERHEAD of the tortoise. Tortoises or humans should never stare at UVB bulbs, so do not attach them at an angle to the side of the enclosure.
Mercury vapor UVB bulbs (MVB's)
Just like with the compact fluorescent UVB bulbs, there has been manufacturing problems with MVB's in the past. For example, some MVB's from batches JI, KI, LI produced after Oct 2009 were affected. These defective MVB's emitted abnormally short wavelength UVB radiation and increased the risk of an eye problem called photo-kerato-conjunctivitis. (Source: UV Guide UK)
Several brands of MVB's are on the market, but it's safest to stick with respected, well-known ones. Zoo Med's PowerSuns and Arcadia's lamps are are popular.
a.) MVB's - dimensions
- Not all MVB's are the same physical size. In other words, MVB's of the same wattage from different manufactures can vary in depth and width. Wider bulbs create larger basking areas which is good. Always use FLOOD bulbs for basking, not spot bulbs.
b.) MVB's - fixtures
- MVB's are wider and deeper than regular household bulbs, so they require larger light fittings. Because MVB's stick out when placed in traditional reptile bulb holders, I like to use the LARGER Zoo Med's Deep Dome or Fluker's Sun Dome fixtures with them. These two domes are almost identical; only the hanger wire shape is different.
- Larger deep dome style bulb holders are long enough to totally cover MVB's. They also have a hanging loop which makes it easy to install them. No slippery clamps. They work well with reptile lamp stands.
- You can also use work lights, utility lights, or brooder lights to hold reptile bulbs, although many of them are too shallow for MVB's. Utility lights can be equipped with fastening clamps, hanging hooks, or both. Utility lights usually have a high wattage rating
- MVB's should always be positioned vertically, in other words, straight down. Not at an angle.
c.) MVB's - wattage
- MVB's have high wattage, typically 100-275W, and they get very hot. Thus, they may not be suitable for very small enclosures. Also double check that your light fixture takes the high wattage of your MVB. For example, deep dome type fixtures are rated for 160W max and mini deep domes for 100W max.
d.) MVB's - minimum distance
- Do follow the MVB installation instructions on the packaging. Do not position the MVB lower than the minimum distance recommended by the manufacturer. Typically, the MINIMUM installation distances are:
- 100W flood MVB - 12" (30 cm)
- 160W flood MVB - 18" (46 cm)
- 275W flood MVB - 24" (61 cm)
- Adjust the bulb position up or down, but above the minimum installation height, to achieve the ideal basking temperature. If the basking area is too hot, you can lift the bulb higher. If the area is too cool, you may need a second MVB or switch to a higher wattage MVB.
- Measure the minimum distance from the top of the tortoise, not from the ground. High wattage MVB's can get very hot and burn the tortoise if placed too low.
- Ideally, use a Solarmeter 6.5 to measure the UVB output (UVI) and adjust the bulb height according to the Ferguson zones (see UV readings page) as well.
e.) MVB's - don't shake
- Avoid touching, bumping, or moving MVB's to prevent an early burnout. It's best to hang up MVB's and not place them on top of screens that get opened all the time.
- If a MVB goes off by itself, wait a few minutes. These bulbs can turn off when they overheat and will later turn back on by themselves. That is, if they are not burned out.
- After being switched off, MVB's will not relight for at least a minute.
Metal halide lamps
Metal halide reptile UVB bulbs are new to the market. They provide visible light, heat, UVA, and UVB and are considered to be superior to MVB's. Metal halides' light output is bright and naturalistic. Unfortunately, their beams are narrow and the UVB decays fast. At least currently.
Two U.S. examples of these lamps are the Zoo Med Powersun H.I.D. Metal Halide UVB Lamp and the Exo Terra Sunray. They must be used with metal halide lamp specific fixtures. Dr Frances Baines and others have started testing these bulbs. You can read their findings and recommendations at the Facebook Reptile Lighting group.
Day & night hours
A common recommendation is to keep indoor tortoise enclosure lights on 12-14 hours a day during the summer and 10-12 hours during the winter.
During the day, the enclosure should be warm and brightly lit to simulate daytime. At night, the enclosure should be dark. Ceramic heat emitters (CHE's) and reptile radiant heat panels are great for nighttime heating because they provide no visible light, only heat. See the heating page for info.
Measuring UVB exposure
a.) Length of time per day
How much exposure to UVB do tortoises need? Traditionally, the UVB exposure was measured in time, but published recommendations varied from a few minutes to hours daily. Some examples are below.
For example, Dr Hartmut Wilke, a German biologist and zoo director (Schildkröten, 2009 / Turtles, 2010), suggests an exposure of 10-20 minutes. He feels that too much UV is pointless and only breaks down the initial level of vitamin D3. His recommendation is to shine the UV light for about 20 minutes during the morning activity period and another 10 minutes during the afternoon activity period.
On the other hand, Andy Highfield of Tortoise Trust (Promoting Proper Bone Development, 2003), suggests that spending 3-4 hours outside daily is enough UVB exposure to produce adequate levels of vitamin D3 in tortoises if you live in an area that has native chelonians.
Read also the Tortoise Trust (TT) forum thread titled "How much UVB exposure" [offsite] from August 2011. That thread includes posts from Frances Baines, M.A., VetMB, MRCVS, of Reptile UV Guide UK. Frances Baines is a retired veterinary surgeon and well-known for her research on reptile UV lighting.
In that same TT thread, Andy Highfield writes about tortoises: "In captivity, you are really looking for an acceptable, functional, 'average' figure, which going by all the evidence I have so far, is likely to be in the 150-180 uW/sq cm range for 30-40 minutes a day at basking temperatures in the 30-34C [86-93.2F] range. Basking temperatures are critical, because temperature is part of the process in converting UVB to usable vitamin D3 by activation of sterols in the skin."
b.) UVB intensity per Fergusons zones
The newest way to measure the needed UVB output, especially indoors, is to use a UVI meter and then apply the Ferguson zone for your species. Most tortoise species, including Indian Star tortoises, fall in the zone 3.
For zone 3 open sun baskers, like Star tortoises, use the "sunbeam method" with the maximum UVI reading of 2.9-7.4 in the basking zone. The highest UVB should be only under the basking bulb and must then fade to nothing over a large gradient. Always provide shady spots in the enclosure as a retreat.
Reptile magazine's Jan 2017 article by Dr Baines has a good overview of Ferguson zones and reptile UV lights. See links below.
Solarmeter 6.2 for measuring UVB and Solarmeter 6.5 for measuring UV index (UVI). In the past, model 6.2 was popular, but currently the model 6.5 is considered to be more useful for tortoise keepers.
You can monitor the intensity and ageing of your UVB lamps with small, handheld devices called UV meters. These meters are also used to install UVB lamps at the proper height to provide the correct amount of UVB based on Ferguson zones.
Solarmeter 6.5 is the most useful one for tortoise hobbyists. This meter is also sold under the Zoo Med label as the Digital UV Index Radiometer (model ST-7).
For info on Solarmeters (models 6.2 and 6.5) and Ferguson zones, along with some outdoor UV measurements, see my UVB & UVI readings page.
UVB & glass
Normal window glass does not transmit UVB. Sunlight through a closed window does not meet tortoises' need for UVB. Even a mesh screen top will filter out some UVB, probably about 30-50% depending on the size of the mesh openings.
You can buy special types of glass or acrylic that allow the transmission of UV radiation, but they are more expensive than regular glass.
There is also a new generation of garden greenhouse films that allow full UVB to pass through. These plastics are especially useful for building outdoor warm up areas for tortoises utilizing polytunnels or small greenhouses.
Links - More info
- The best source for the latest, up-to-date info on reptile UVB lamps is the Reptile Lighting group on Facebook. Dr Frances Baines, a well known researcher on reptile UVB lighting, is a regular poster there.
- The UVB Meter Owners Yahoo group created in 2003 is rather quiet now. Discussions seem to have moved to the above Facebook group.
Links - Articles
- JZAR Journal (Journal of Zoo and Aquarium Research) - How much UV-B does my reptile need? The UV-Tool, a guide to the selection of UV lighting for reptiles and amphibians in captivity; guide to reptile UVB for zoos, by Dr Frances Baines et al., 2016
- Reptiles Magazine - An In-Depth Look At UV Light And Its Proper Use With Reptiles, by Dr Frances Baines, Jan/Feb 2017
- UV Guide UK - a well-regarded website about reptile lighting, by Dr Frances Baines & others
- Zoo Biology - Voluntary exposure of some western-hemisphere snake and lizard species to ultraviolet-B radiation in the field: how much ultraviolet-B should a lizard or snake receive in captivity?; Ferguson zones are based on this reptile UVB research paper, by Dr Ferguson et al., 2009
- Zoo Med - UVI meter instructions, UV index (UVI) and Ferguson zones, 2013
- Zoo Med - Powersun H.I.D. lamp (metal halide) instructions with Ferguson zones
Related page: UV readings outdoors (UVB & UVI w. Solarmeters 6.2 & 6.5)