viewtopic.php?f=34&t=114123
i'm not familiar with Zilla t8 tubes , does 50 in spec indicate it's rated at 5% UVB output..... if so, it's too weak wrt UVA & UVB output , beardies, ESP hatchlings and fast growing juveniles, need at least 10% UVB & 30% UVA .
checked 50 ==> 50 microwatts / sqcm @ 12inches - see
http://www.zillarules.com/all-products/lighting-heating/t8-fluorescent-bulbs , that is quite inadequate for a bearded dragon. The beardie would have to be placed closer than 4 inches from the tube to get healthy UVA & UVB exposures.
just because their advertising say their lights are suitable doesn't make it so. This one is definitely NOT.
Geographically USA's deserts are at much higher latitudes than Australia's which are located in the tropics so UV exposures are very much higher in Australia's deserts even though USA's deserts are at higher altitudes .
I recommend returning it to shop and exchange for a similar wattage t8 with at least 10% UVB output rating.