Best UVB for a Crested Gecko (Do They Even Need It?)

Do crested geckos need UVB?

No, not as a hard requirement, and anyone who tells you a crestie will die without it is overstating it. A crested gecko fed a quality complete diet that already contains D3, like the common powdered gecko diets, does fine with no UVB at all. That's how the animal got its reputation as a no-lights beginner pet.

"Not required" and "not worth it" are different things, though. Experienced keepers add a low level of UVB because it lets the gecko produce and regulate its own D3 rather than depending on the exact dose in a powder. That quietly removes the risk of over-supplementing D3, a real problem that can lead to an incurable gout-type illness. One keeper who has run low UVB alongside a D3 diet for years reports no health issues at all. At the right low level it's upside without much downside.

Keep it low

This is where people hurt their animals. A crested gecko is a shade species. It lives in dappled forest light, not desert sun, so it needs a fraction of the UV a bearded dragon does. A strong desert bulb, the 10, 12, or 15 percent tubes sold for dragons, is far too much over a crestie.

What you want is a low-output linear T5 UVB tube in the 2.4 to 7 percent range. In Ferguson-zone terms a crestie is a low-UV animal, and keepers who measure aim for a UV index only a little above 1 at the spot the gecko basks. More isn't better here. More is a stressor.

2.4% or 7%? Your mesh decides

Once you know you want a low tube, which low tube isn't a matter of taste. It depends on what the light has to pass through to reach the animal.

• Black mesh: go 7%. Black mesh blocks somewhere between half and two-thirds of the UV. Put a 2.4 percent tube on top of black mesh and, in keepers' words, it does almost nothing for the animal. The 7 percent survives the mesh and lands in the right range.
• Silver mesh or no mesh: go 2.4% to 5%. Silver mesh blocks less, around a third to a half, and mounting the tube inside the enclosure blocks nothing. There the 7 percent is too strong and the 2.4 to 5 percent is correct.

The tube can sit right on top of the mesh, which is how most keepers run it. A UVB tube gives off almost no heat, so it's no burn risk up there. Distance matters as much as percentage: the further the gecko's highest perch sits from the tube, the weaker the dose, so a taller enclosure leans toward the stronger tube.

Linear T5, never a coil

Whatever percentage you land on, buy a linear tube, not a compact or coil bulb. Same hard rule as for any reptile UVB. Coil bulbs light only a tiny patch and aren't trusted to deliver safe, even output. Keepers put it plainly: any brand of linear UVB tube is fine as long as the percentage and fitting are right, but do not use compact bulbs. T5 beats the older T8 because it holds output longer, so you replace it about once a year instead of every six to eight months.

The brand problem, and what to buy

Here's the frustrating part. The tube the crested gecko community recommends most is the Arcadia ShadeDweller, and it's good. But Arcadia's small UVB kits are chronically hard to buy through normal online retail. Keepers routinely report finding them only at a specialty pet chain rather than on Amazon, which does you no good if you're shopping from your couch.

Two honest workarounds. The reliable one: the Zoo Med ReptiSun 5.0 in a linear T5 is, in the words of keepers who use both, "exactly the same product" as the Arcadia for the price difference, and it's easy to buy. That's the pick most people should make. The other is Arcadia's newer LumenIZE dimmable version, which IS readily available, but it comes with real caveats covered next, so buy it with eyes open rather than as the default.

A warning on the dimmable "LumenIZE" version

It's the Arcadia option you can buy easily, so it's tempting. Know what keepers report about it specifically. The LumenIZE is the dimmable ShadeDweller with an app and a slow sunrise-sunset ramp. Multiple keepers describe functional problems: bulbs with unexpectedly short lifespans, odd noises, unresponsive customer support. One owner watched replacement bulbs die in as little as two to three months. There's also a credible argument that the headline slow-ramp feature is more marketing than meaningful, that it doesn't replicate natural UVI changes.

None of that is dangerous to the gecko, and plenty of units work fine. It does make the dimmable version a gamble in a way the plain tube isn't, so we'd treat it as a considered choice rather than the safe default. The safe default is a plain low-output linear tube.

UVB changes how you supplement

Adding UVB changes your calcium and vitamin routine, which surprises new keepers, and getting it wrong undoes the benefit.

UVB lets the animal make its own D3, so you stop force-feeding D3. With a good UVB setup, keepers dust insects with plain calcium, not calcium with added D3, to avoid stacking D3 on top of D3. If black mesh weakens your UVB a lot, a small amount of dietary D3 is still fine and even sensible, and a complete gecko diet that already contains modest D3 is generally okay alongside UVB. A low-D3 calcium supplement exists specifically for UVB setups for this reason. In doubt, err toward less D3. You can't overdose UVB. You can overdose a powder.

What we'd buy

Give your crested gecko a low-output linear T5 UVB tube: the 7 percent if it sits on black mesh, the 2.4 to 5 percent otherwise, never a coil, aiming for a gentle UV index just above 1 where the gecko perches. Not mandatory. Still a cheap upgrade to the animal's health, and it makes your supplementing more forgiving.

We'd buy the Zoo Med ReptiSun 5.0 linear T5 unless you have a specific reason not to, because the more-loved Arcadia ShadeDweller is a pain to purchase and the easy-to-buy Arcadia LumenIZE carries a real reliability question mark. Then switch your insect dusting to plain calcium.