Arcadia vs Zoo Med UVB for bearded dragons

Bad lighting is the single most common husbandry mistake with bearded dragons — incorrect UVB or basking temperatures are the leading cause of metabolic bone disease and chronic illness, and most owners don't realise anything is wrong until real damage has already been done. You're comparing Arcadia and Zoo Med tubes, which tells me you're already thinking about this seriously — good. To give you a straight answer on value, I need a few details: what size is your enclosure, what are you currently running for UVB and basking (brand and wattage if you know them), and how old is your dragon?

That T8 is well overdue — UVB output degrades significantly after 6 months even when the bulb still lights up, so at 18 months he's been running on very little useful UVB for a while. On your direct question: switch to Arcadia, and go T5 HO rather than T8. My specific recommendation is the Arcadia Dragon Lamp T5 HO 12% — available in a 39W version that suits a 4x2x2 perfectly. Here's why it wins on value despite the higher upfront cost: T5 HO tubes maintain their UVB output for 12 months rather than the 6-month replacement cycle of T8s, so over two years you're replacing half as often. The 12% output is calibrated specifically for desert species like bearded dragons and delivers effective UVB deeper into the enclosure, which matters in a 2-foot-tall viv. Zoo Med's T5 HO ReptiSun 10.0 is a decent alternative but Arcadia's consistency and documented output data put it ahead. For a 2-year-old dragon in a 4x2x2, the Arcadia Dragon Lamp T5 HO 12% 39W is the right call.

You can't reuse a T8 fitting for a T5 tube — they're not compatible. T5 and T8 tubes use different ballasts and end caps, so you'll need a dedicated T5 HO controller. Arcadia sells their own T5 HO light unit as a kit that includes both the controller and the tube, and that's actually the most economical way to buy in — it works out cheaper than buying them separately. The Arcadia ProT5 Kit is what to look for on Amazon UK; it comes in a 39W 39-inch version that fits a standard 4-foot wide viv with room to spare. Factor that into your budget comparison, but remember you're also buying two years of reliable output versus replacing a T8 every six months.

With the Arcadia Dragon Lamp 12% T5 HO, aim for 25–40cm between the tube and your dragon's back at his closest basking point — that's the zone where UVI output hits the optimal range of 3–6 for a bearded dragon. In a 4x2x2 with a mesh or partial mesh top, mounting the tube inside the enclosure rather than on top makes a significant difference; mesh cuts UVB transmission by around 30–50%, so if yours is going through mesh you may need to drop toward the 25cm end of that range. If the tube is mounted directly inside with no mesh between it and the dragon, 30–35cm is a solid target. Keep the basking spot within that UVB zone too — he should be able to thermoregulate and UV-regulate in the same area at the same time.

The wattage alone doesn't tell us much — it's the temperature it produces that matters. For a 2-year-old adult bearded dragon you want a basking spot surface temperature of 40–42°C, with the cool end sitting around 26–28°C. If your 100w bulb is hitting those numbers, keep it. Use an infrared temperature gun to measure the actual surface where he basks rather than an ambient thermometer — that's the number that counts. If it's running too hot or too cool, adjust wattage accordingly. A simple halogen flood bulb works just as well as branded reptile basking bulbs at a fraction of the cost, so don't feel you need to spend on a named product there. Sort the UVB first — that's the priority.