XmanN: Did you look up that information i told you about the other day? Check this out:
The ideal 'range' of UV for increase in THC is 300-320 nm. However, it is thought (and has been found in studies) chemical precursors convert into THC with greater efficiency around 280-290 nm. Both those ranges work in synergy in my opinion.
Benchmarks:
Highest ideal UV-b irradiance[2] = 370 uW/cm^2 (rounded down)
Lowest ideal UV-b irradiance[3] = 190 uW/cm^2 (rounded up)
Figure 16 shows one of the "higher output" SB lamps (ref. BM2) in use in the large bearded dragon vivarium for which it was supplied. In this set-up, the upper basking branch is not directly under the lamp, but close to the front of the vivarium. Since the beam produces a three-dimensional "cone" of UVB radiation, this puts the centre of the branch in the area receiving between 50 - 300 uW/cm². The lower branch, directly under the lamp, also receives good UVB coverage.