Bearded dragon & water dragon lighting setup

Running a bearded dragon and a water dragon off the same timer strip is a real problem — these two species need meaningfully different photoperiods and UV cycles, and locking them to identical schedules is likely already causing low-level stress and suppressed immunity in at least one of them. Getting heating and UV lighting right is honestly the single most important factor in reptile health — metabolic bone disease, respiratory infections, and lethargy are almost always rooted in incorrect lighting or temperature before anything else. To give you specific advice: what enclosure sizes are you working with, and what bulbs do you currently have running for each vivarium?

Good news — your bulb choices are actually solid for both species. The 12% for the beardie and 6% for the water dragon are correct. The problem is entirely the shared timer. Your adult beardie ideally wants 13–14 hours of light in summer ramping down to around 10–11 in winter, which closely mimics the Australian interior. Your sub-adult water dragon needs higher humidity and slightly longer photoperiods year-round — around 12–13 hours — but the bigger issue is they benefit from a slightly staggered ramp-up in the morning to allow the enclosure humidity to rise before the basking heat peaks. Chaining them together removes any ability to manage either species properly. How are you currently managing the basking bulb and UVB together — are they both on the same channel of the timer?

Very common setup and easy to fix. Ideally you also want the UVB on for slightly longer than the basking bulb in both vivariums — turning basking heat on 30 minutes after UVB starts and off 30 minutes before it ends better replicates natural conditions and reduces thermal stress. To do all of this properly you need independent control per vivarium, and ideally per circuit within each viv. The product I'd recommend is the Inkbird IHC-200 digital timer — it's a dual-channel timer so one unit gives you independent scheduling for two separate circuits. Buy two of them, one per vivarium, and you can set UVB and basking on separate channels for each enclosure. They're reliable, easy to programme, and about £20–25 each on Amazon UK. That's roughly £45 total to properly fix the lighting management for both animals.

Shift gradually — about 15 minutes per week is a comfortable pace for both species. Start by splitting them onto separate timers first, keeping the same 12-hour schedule for both while they adjust to the new hardware. Then nudge the beardie up toward 13.5 hours over about six weeks. The water dragon can stay closer to 12–12.5 hours. The basking offset — UVB on first, then basking — you can implement immediately once the dual-channel timers are in, that won't cause any stress at all. Keep an eye on your water dragon's shedding and appetite over the next few weeks; they're the more sensitive of the two and you'll notice improvements there first if the lighting regime was causing any background suppression.

Yes, significantly. Fine mesh can block 30–50% of UVB transmission depending on the weave density, which is a known issue with water dragon and chameleon keepers. With a 6% T5 that loss matters. The practical fix is to ensure the T5 tube is mounted inside the enclosure rather than on top of the mesh, or as close to the mesh as possible with no plastic diffuser between the bulb and the animal. Also measure the actual basking distance from bulb to the dragon's dorsal surface — for a 6% T5 inside a mesh enclosure you want that at no more than 30cm. If repositioning isn't possible, stepping up to an Arcadia T5 12% for the water dragon is a reasonable move — they're found in high UV environments too and sub-adults particularly need strong UV for bone development. Worth checking the Arcadia Ferguson Zone guidance for Chinese water dragons to confirm your current setup is hitting the right UV index at basking height.