The three UVB families I would compare
Arcadia ShadeDweller 7%
Arcadia specifically designed ShadeDweller 7% around crepuscular species and publishes leopard-gecko-oriented distance guidance.
Buy it when: you are lighting leopard geckos or similar lower-UVI species at an appropriate distance
Watch for: small enclosures can make even a lower-output lamp too close
Arcadia ProT5 6% / 12%
ProT5 uses a strong reflector and is available in forest/desert/dragon output classes, making it easier to keep one fixture ecosystem across several reptile setups.
Buy it when: you want multiple output choices with published UVI-distance tables
Watch for: the exact percentage must be matched to enclosure geometry
Zoo Med ReptiSun T5 HO
ReptiSun T5 HO 5.0 and 10.0 are repeatedly referenced in modern care guidance for snakes and lizards. The main advantage is dependable availability and a large body of keeper experience.
Buy it when: you want a widely stocked, proven UVB platform
Watch for: use Zoo Med/ReptiFiles-specific distance guidance instead of copying Arcadia tables
Arcadia's advantage is data visibility
Arcadia publishes ProT5 UVI measurements at multiple distances and states the reflector system used. That does not eliminate the need to measure your enclosure, but it gives the buyer a much better starting point than vague “desert” labels.
Zoo Med's advantage is ubiquity
ReptiSun is easy to find from major reptile and general retailers in the U.S. Replacement tubes and fixtures are familiar to keepers, which matters because UVB is not a one-time purchase.
ShadeDweller fills a lane Zoo Med shoppers often solve differently
Leopard geckos and other crepuscular species benefit from lower target UVI than a bearded dragon. ShadeDweller packages that idea into a purpose-built lower-output system, whereas a ReptiSun buyer may choose a lower-percentage tube and adjust distance.
Fixture matters
A good reflector pushes more useful UV downward. If you put the same tube in a different fixture, or mount it through denser mesh, the animal may receive a different UVI. Treat the bulb and fixture as a system.
The part that matters more than the product name
Measure the enclosure, not the marketing label
“40 gallon,” “120 gallon,” and similar labels are convenient shorthand, but reptiles experience length, width, height, ventilation and usable surface area. Two tanks with the same nominal volume can create completely different thermal gradients. Before you buy a heater, lamp or enclosure accessory, write down the actual internal dimensions and the distance from the animal’s highest usable basking surface to the lamp.
Build the gradient before adding the animal
A good reptile setup offers choices. The warm end should be meaningfully warmer than the cool end, humidity should be appropriate to the species rather than uniform everywhere, and the animal should be able to move into shade. Run the enclosure empty for several days, log temperatures at animal level, and change wattage, lamp height or ventilation before the reptile moves in.
Use instruments, not your hand
Human skin is a poor reptile thermometer. Use digital probe thermometers for ongoing air or hide measurements and an infrared temperature gun for surfaces. If you are dialing in UVB, lamp output is affected by fixture, mesh and distance; a Solarmeter is the most direct way to measure UVI instead of guessing from a bulb percentage.
Heat must be controlled
Any heat source capable of overheating an enclosure needs appropriate control. On/off thermostats are suitable for certain non-light-producing or supplemental devices such as heat mats; proportional/dimming control is the better match for devices whose output should be modulated smoothly. A thermostat is a safety/control layer, not a substitute for independent thermometers.
How to test the setup after the box arrives
Assemble the hardware with no animal inside. Put the substrate and hardscape in their final positions because a raised basking rock or four inches of substrate changes the distance to the lamps. Run the normal day cycle, then record the warmest surface, warm-side air, cool-side air and humidity. Repeat after the room has had time to cool overnight. If the enclosure sits near a window or exterior wall, repeat during the hottest and coldest part of the day.
Change one variable at a time. Raising a lamp, changing wattage, covering part of a screen or adding ventilation can all affect multiple readings. If you change three things together, you will not know which one solved the problem. Once the enclosure is stable, photograph the probe locations and write down the normal range; that makes it much easier to spot a failed bulb, moved probe or seasonal room change later.
What I would not buy just because it appears in a search result
Skip heat rocks, unregulated heating pads, colored night bulbs, tiny analog stick-on gauges and mystery-brand UVB lamps with no useful output data. Also be skeptical of “all-in-one” reptile kits that pair an undersized tank with reptile carpet and a single bulb. The easiest affiliate link to click is not necessarily the product that creates a viable habitat.
When two products are close, favor the one that is easier to measure, replace and service. Standard bulb sizes, replaceable T5 tubes, accessible probes, removable substrate barriers and available replacement nozzles matter more after a year than flashy packaging on day one.
Before checkout: setup checklist
- Actual enclosure dimensions fit the species and adult size
- Warm and cool zones can both exist at the same time
- Heat source has appropriate thermostat/control
- UVB type, fixture, mesh loss and distance have been considered
- At least two reliable temperature readings are available
- Humidity can be measured digitally at animal level
- Hides/cover are available in more than one thermal zone
- Substrate matches the species rather than pet-store convenience
- All hot bulbs inside enclosures are physically guarded
- Cords, probes and misting lines are secured against the animal
Frequently asked questions
Is Arcadia UVB better than Zoo Med?
Both are reputable. Arcadia offers excellent published output guidance; Zoo Med offers strong availability and a proven ReptiSun line.
Can I use Arcadia distance numbers for a Zoo Med lamp?
No. Use guidance for the exact lamp and fixture or measure with a Solarmeter.
Which is better for leopard geckos?
Arcadia ShadeDweller is specifically designed around lower-UVI crepuscular use, but other proven lamps can work when positioned correctly.
Which is better for bearded dragons?
A strong linear T5 system from either brand can work when it produces the target UVI at the basking surface.
Primary husbandry and manufacturer sources
- Arcadia Reptile — ShadeDwellerPro 7%
- Arcadia Reptile — ProT5 UVB
- ReptiFiles — Leopard Gecko Temperatures, UVB & Humidity
- ReptiFiles — Corn Snake Temperatures, UVB & Humidity
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