Bearded dragon and blue-tongue skink lighting

Running a bearded dragon and a blue-tongue skink in the same room is actually a smart setup — but lighting bleed between enclosures is a real problem that most people underestimate. Bad lighting is the single most common husbandry mistake with bearded dragons specifically: incorrect UVB or basking temperatures cause metabolic bone disease and chronic illness that owners often don't spot until significant damage is done. Before I help you plan this properly, tell me: what size are each of their enclosures, what UVB and basking bulbs are you currently using (brand and wattage) for each, and how old is the dragon?

Right, a few things to untangle here. Your instinct is correct — the 46cm 12% T5 is undersized for a 4x2x2. For an adult dragon in that enclosure you want the Arcadia T5 HO 12% 1.2m tube, which covers the full length and gives your dragon a proper UV gradient from high exposure near the lamp down to shade. That's the fix that matters most urgently. The skink's 6% T5 is appropriate for a blue-tongue. Now on the cross-interference question: at 1.5 metres apart with closed wooden vivs, UVB bleed between enclosures is essentially zero — T5 tubes don't project usefully beyond the enclosure they're mounted in. The concern you actually need to manage is heat and light cycle timing. Are both enclosures on the same on/off schedule, and is there any shared ambient heat buildup in the room during summer?

That worry is understandable but you can let it go — enclosed wooden vivs are opaque to UVB entirely, and even with mesh tops, meaningful UVB doesn't travel 1.5 metres and penetrate another enclosure. Your gradients are completely isolated. The shared timer is fine and actually keeps their circadian rhythms stable, which matters for both species. The 26-27°C ambient is something to watch with the dragon — on very hot days that can push the cool end of the viv too warm and collapse his thermal gradient, meaning he can't thermoregulate properly. A clip fan in the room to keep air moving helps. The single change I'd make right now is upgrading the dragon's UVB lamp. The one to get is the Arcadia T5 HO Dragon 12% UV Lamp 1.2m — fits your 4x2x2, gives full-length coverage, and Arcadia's output consistency on the 12% is significantly better than the 6% tube scaled up. Replace it every 12 months regardless of whether it still glows. For your skink, nothing needs to change.

Yes, and this is where a lot of setups go wrong even with the right bulb. The T5 HO 12% should be mounted inside the enclosure, not on top of mesh — mesh blocks around 30-40% of UVB output depending on type. Position it so the tube runs the full length, about 35-40cm from where the dragon basks. At that distance with the 12% you're hitting a Ferguson Zone 3-4 UV index at the basking surface, which is appropriate for a bearded dragon. Your basking spot and UVB source should be at the same end of the viv so the dragon is getting UV exposure while he thermoregulates — that's how it works in the wild. Don't place them at opposite ends. Cool end stays dark and UV-free, which is exactly what he needs to regulate his exposure naturally.

Two things worth checking while you have everything out. First, verify your basking surface temperature with a temperature gun rather than an ambient thermometer — dragon basking spots should be 40-42°C at the surface where he sits, not the air above it. Surface temps are consistently lower than people assume with ambient probes. Second, if you don't already have a Solarmeter 6.5 UV index meter, it's the only reliable way to confirm your UVB gradient is actually what you intend — UV output varies by reflector quality, tube age, and mounting position in ways that guessing can't account for. It's a one-time purchase that protects both animals long-term. Your skink setup sounds solid, the dragon enclosure is the one that needed attention — and now you've got a clear plan.