Bearded dragon UV bulb that lasts

A UV bulb failing within weeks is unfortunately common with budget options — and the problem isn't just that it stopped glowing, it's that UVB output often drops well before the visible light does, meaning your beardie may have been running a deficit without you even knowing. Reptile welfare is almost entirely determined by getting the environment right: temperature gradient, UV lighting, humidity, and substrate all need to match the species' natural habitat, and for bearded dragons that means serious UVB provision. Getting it wrong causes chronic stress, metabolic bone disease, and immune issues over time. So — how old is your beardie, what size is the enclosure, and are you also looking at the fixture or just the bulb replacement?

Good that you have a UVI meter — that's exactly how you catch this, and a lot of owners don't bother. A zero reading after three weeks on a budget bulb is a failure, not bad luck; those bulbs often have no meaningful phosphor quality control. For a 2-year-old beardie in a 4-foot enclosure, you want to be hitting UVI 3–4 in the basking zone, which requires a proper high-output T5 tube. What bulb brand was the one that failed?

The one I'd point you to without hesitation is the Arcadia Dragon Lamp T5 HO 14% UVB, 39W in the 865mm size for a 4-foot setup. Arcadia is the benchmark for reptile UVB in the UK — they publish independent spectral data, the phosphor quality is consistent batch to batch, and their T5 HO tubes genuinely maintain output across the bulb's rated lifespan rather than dropping off a cliff at week three. The 14% rating is specifically formulated for desert species like bearded dragons and will give you the UVI gradient you need across the enclosure when mounted correctly inside the canopy. Replace it every 12 months regardless of whether it's still glowing — UVB output degrades before the visible light fails, which is exactly what bit you last time.

With the Arcadia 14% T5 HO inside a reflective canopy, you're typically looking at 25–35cm from the tube to the basking surface to land in the UVI 3–4 zone. But measure it with your meter rather than guessing — every setup is slightly different depending on the reflector quality and whether there's mesh between the tube and the animal. Mesh can cut UVI by 30–50% depending on the gauge, so if you have a mesh top, mount it closer. Aim for UVI 3 at the basking spot as a minimum, with a gradient down to 0–0.5 at the cool end so he can self-regulate.

Good call. Set a reminder for 12 months and retest with your meter every couple of months in between — UVI drift is real even on quality tubes. Your beardie should be back to normal behaviour within a few days of proper UVB provision.