How Much UVB Does Your Reptile Actually Need?
The Zoo Med ReptiSun 10.0 T5 HO is our top pick because a linear tube spreads usable UVB across the whole basking area rather than one spot. The Arcadia ProT5 12% Kit is the strongest option for desert species, and the Zoo Med PowerSun combines heat and UVB.
For most reptile setups the Zoo Med ReptiSun 10.0 T5 HO is the lamp to fit, because a linear tube gives an animal a usable UVB gradient to move through instead of a single hot spot. Desert species do better under the Arcadia ProT5 12% Kit, while the Zoo Med PowerSun UV suits keepers who want heat and UVB from one fixture.
Getting UVB right is unusually easy to get wrong, because output drops sharply with distance and mesh screening, and lamps stop producing useful UVB long before they stop making visible light. We compared published output percentages, lamp formats, recommended mounting distances, stated lifespans and fixture compatibility across current products, and weighed those against what keepers report about output falling off, mesh losses and species specific results.
The top picks, ranked
Zoo Med ReptiSun 10.0 T5 HO UVB Lamp
A high output linear tube that projects usable UVB well down into an enclosure while spreading it along the length, which lets an animal self regulate exposure. It is the format most modern husbandry guidance points toward. Requires a T5 HO fixture with a reflector, which is a separate purchase but roughly doubles the effective output.
Pros
- Even coverage lets animals self regulate
- High output reaches deep enclosures
- Widely available in multiple lengths
Cons
- Needs a separate T5 HO fixture
- Reflector is essential for full output
Arcadia Reptile ProT5 12% UVB Kit
Sold as a complete kit with a highly polished reflector fixture, which removes the guesswork of matching lamp to housing. The 12 percent output suits bearded dragons, uromastyx and other high UV requirement species when mounted at the correct distance. Arcadia’s published distance guidance is unusually clear, which helps set the basking height properly.
Pros
- Complete kit with matched reflector
- Output suits high UV desert species
- Clear mounting distance guidance
Cons
- Too strong for low UV requirement species
- Higher outlay than a bare lamp
Zoo Med PowerSun UV Mercury Vapor Lamp
Produces heat, UVA and UVB from a single self ballasted bulb, which simplifies a setup to one fixture. That convenience is also its limitation, since heat and UVB output cannot be adjusted independently. Best suited to large, tall enclosures where the required mounting distance is achievable without cooking the basking spot.
Pros
- Single lamp covers heat and UVB
- Strong output for large enclosures
- Simplifies fixture and wiring
Cons
- Heat and UVB cannot be tuned separately
- Unsuitable for small enclosures
Exo Terra Solar Glo Mercury Vapor Lamp
A mercury vapour lamp with a broad daylight spectrum that makes enclosures look considerably better while providing heat and UVB. Like all lamps of this type, it needs height to spread its output safely. Keepers report good plant response in planted vivariums thanks to the visible light quality.
Pros
- Excellent visible light quality
- Supports live plants in vivariums
- Heat and UVB from one source
Cons
- Requires substantial mounting height
- Runs hot enough to need careful placement
Zoo Med ReptiSun 5.0 Compact Fluorescent UVB Lamp
A screw fitting compact lamp for enclosures where a linear tube will not fit, such as small gecko or amphibian setups with lower UV requirements. Output is concentrated rather than spread, so placement matters more than with a tube. The 5.0 rating suits forest and crepuscular species rather than desert reptiles.
Pros
- Fits standard screw sockets
- Right output level for low UV species
- Works in small enclosures
Cons
- Concentrated output rather than a gradient
- Coverage area is small
REPTI ZOO T5 HO Reptile UVB Bulb
A linear T5 HO tube at a noticeably lower outlay than the established brands, available in both 5.0 and 10.0 equivalents. Output consistency is the usual question with value lamps, and keepers who own a UV meter tend to check these more carefully. As a replacement tube on a schedule it represents solid value.
Pros
- Considerably lower outlay per tube
- Available in several lengths and outputs
- Fits standard T5 HO fixtures
Cons
- Output consistency varies more between units
- Less published testing than premium brands
LUCKY HERP UVA UVB Mercury Vapor Bulb
An inexpensive route to combined heat and UVB for keepers with a large enclosure and a limited outlay. It works as intended, though lifespan and output consistency sit behind the premium mercury vapour lamps. A ceramic socket is mandatory, since standard plastic fittings are not rated for the heat.
Pros
- Low outlay for a combined lamp
- Multiple wattage choices
- Adequate output for large enclosures
Cons
- Shorter useful life than premium lamps
- Output varies more between individual bulbs
How they stack up
| # | Model | Output | Best for | Score | Price |
|---|---|---|---|---|---|
| 1 | Zoo Med ReptiSun 10.0 T5 HO UVB Lamp | 10 percent UVB | Best overall | 9.4 | Check price |
| 2 | Arcadia Reptile ProT5 12% UVB Kit | 12 percent UVB | Best for desert species | 9.2 | Check price |
| 3 | Zoo Med PowerSun UV Mercury Vapor Lamp | Self ballasted mercury vapour | Best combined heat and UVB | 9.0 | Check price |
| 4 | Exo Terra Solar Glo Mercury Vapor Lamp | Mercury vapour, self ballasted | Best for large tall enclosures | 8.8 | Check price |
| 5 | Zoo Med ReptiSun 5.0 Compact Fluorescent UVB Lamp | 5 percent UVB | Best for small enclosures | 8.6 | Check price |
| 6 | REPTI ZOO T5 HO Reptile UVB Bulb | T5 HO linear tube | Best value tube | 8.3 | Check price |
| 7 | LUCKY HERP UVA UVB Mercury Vapor Bulb | Mercury vapour, self ballasted | Best budget mercury vapour | 8.0 | Check price |
How to pick the right one
Match output percentage to the species, not to the enclosure UVB lamps are rated by the percentage of output in the UVB range, and species requirements vary enormously. Desert basking reptiles such as bearded dragons need high output lamps at appropriate distance, while crested geckos, many snakes and amphibians need low output or none at all. Too much UVB causes real harm, so start from published guidance for your species rather than assuming stronger is safer.
Distance and mesh cut output more than people expect UVB intensity falls off rapidly with distance, so a lamp mounted too high delivers almost nothing at the basking spot. Enclosure mesh compounds this, with fine screens absorbing a substantial share of what passes through. Mount inside the enclosure where the design allows, use the widest gauge mesh that safely contains your animal, and follow the manufacturer’s published distance guidance for the specific lamp.
Linear tubes versus compacts versus mercury vapour Linear T5 tubes give a broad gradient across the enclosure, which lets the animal choose its exposure and is the format most current guidance favours. Compact screw fittings are convenient in small enclosures but produce a narrow, concentrated beam. Mercury vapour bulbs combine heat and UVB in one fitting, which suits large tall enclosures but removes your ability to adjust heat and UVB independently.
Replace on a schedule, not when the light dies The critical point about UVB lamps is that they continue producing visible light long after UVB output has fallen below useful levels. Most fluorescent and T5 lamps need replacing roughly annually, and mercury vapour lamps on a similar or shorter cycle. Write the installation date on the lamp with a marker, or keep a note, because relying on appearance leads to animals living under a lamp that stopped working months earlier.
Frequently asked questions
Do all reptiles need UVB?
No. Diurnal basking species such as bearded dragons, tortoises and many lizards need it for calcium metabolism. Some nocturnal species and many snakes have much lower requirements, though current research suggests low level UVB benefits more species than once thought.
How often should UVB bulbs be replaced?
Roughly every twelve months for most fluorescent and T5 lamps, sooner for some mercury vapour bulbs. Output falls steadily even while the lamp still lights, so replacement is driven by time rather than failure.
Does mesh block UVB?
Yes, significantly. Fine screens can absorb a large share of the output, so mount lamps as close as is safe, use coarser mesh where possible, or mount the fixture inside the enclosure if the design allows it safely.
Can UVB pass through glass?
Standard glass blocks most UVB, which is why a lamp placed outside a glass lid delivers almost nothing. This is also why a window does not provide usable UVB for a reptile.
Is a UVB and heat combination bulb a good idea?
It is convenient for large tall enclosures, but it ties heat and UVB together. If your basking temperature is correct at a distance where UVB is too weak, or vice versa, separate lamps give you the control to fix it.
How do I know if the UVB level is right?
The only reliable method is a UV index meter placed at the basking spot. Without one, follow the manufacturer’s published distance guidance carefully and replace lamps on schedule.
Can too much UVB harm a reptile?
Yes. Excessive exposure can cause eye and skin damage. Providing shaded areas and a proper gradient lets an animal move away from the light, which is why linear tubes with good coverage are generally safer than a single intense spot.
Do UVB lamps need to be on all day?
They should follow a day and night cycle, typically ten to twelve hours on, adjusted seasonally for some species. Leaving UVB on continuously prevents proper rest and offers no benefit.
Our take
The Zoo Med ReptiSun 10.0 T5 HO is the UVB lamp we would fit in most enclosures, because a linear tube gives animals a gradient to choose from rather than one intense spot. Desert species are better served by the Arcadia ProT5 12% Kit, and the Zoo Med PowerSun UV makes sense in large tall enclosures where one fixture is simpler.
