Best T5 HO UVB for 6ft bearded dragon enclosure

Bad lighting is the single most common husbandry mistake with bearded dragons — incorrect UVB output or basking temperatures are behind most cases of metabolic bone disease, and owners often don't realise anything is wrong until real damage has already been done. Moving to a 6-foot enclosure is actually a great opportunity to get this right from the start, because your old fixture almost certainly won't cover the new footprint properly. To point you to exactly the right setup: what bulbs are you running now — brand and wattage — and how old is your dragon?

Good — Arcadia 12% is a solid choice and the fact you've been running T5 HO already means your dragon is used to proper UVB exposure, which is ideal. The 24-inch tube in a 4-foot enclosure was already a bit short for full coverage, and in a 6-foot viv it simply won't do the job at all. You'll want a tube that runs roughly two-thirds the length of the enclosure at minimum, ideally the full 4 feet. One more question: what are you using for the basking end — a separate halogen or combined MVB?

Perfect setup — keeping UVB and basking separate gives you much better control over each independently. For the 6-foot enclosure, I'd go straight to the Arcadia T5 HO Dragon Lamp 14% 54W in the 46-inch (T5 HO 1200mm) size with the Arcadia ProT5 controller unit. Here's why that specific combination makes sense for your dragon: at 3 years old he needs consistent Ferguson Zone 3 UVB exposure, and the 14% tube paired with a quality reflector will give you a proper UVI gradient across the full length of the viv — strong UVB at the basking end, lower exposure at the cool end so he can self-regulate. The 46-inch tube on a 6-foot enclosure covers the run perfectly. The Arcadia ProT5 Kit 46-inch with 14% Dragon Lamp is available on Amazon UK as a complete unit and it's genuinely the best-value, best-performing option for an adult dragon in a large enclosure.

It's a reasonable concern but in practice it's not a problem — the percentage refers to UV index output, and in a larger enclosure the gradient naturally spreads the exposure out more. Your dragon will move toward or away from the tube to self-regulate, exactly as he would in the wild. That said, if you want to be cautious, simply position the tube a couple of inches higher in the first two weeks to soften the intensity slightly while he acclimatises to the new space. After that, drop it to the standard mounting height in the Arcadia guidelines. You won't be overwhelming him — you'll actually be giving him what a wild adult dragon needs.

Replace the Arcadia T5 HO tube every 12 months regardless of whether it still appears to be producing visible light. UVB output degrades steadily over time even when the tube looks fine — by month 12 output has typically dropped enough that your dragon is being underserved, which is exactly the slow-burn problem that leads to MBD in otherwise well-kept animals. Mark the replacement date on the fixture when you install it. It's the single easiest thing you can do to protect him long term.