Just to add my $.02 I have one 26w reptiglo 10.0 that I run the full 12 hours the lights are on, about 3-4 inches from the canopy (as the levels of uv-b it produces are nowhere near what outdoor sun exposure is, I see no reason to turn it off as I see no way of overdosing with a bulb that small) and I've noticed that the buds closest to it are noticeably frostier than the buds furthest away. (Also I've noticed that buds closer to the 6500K bulb have a similar increase in trichome density when compared to the buds closer to the 2700K bulbs, my guess is that it is from the extra uv-b the 6500K's put out)
On your 65K bulb. Yes it will have SOME extra UVnm range light production (you've found that out). Bulbs that run the "blue" range of the spectrum produce the UV in A,B and C nm ranges. Like I said you can get this same effect with HID lighting, using your MH bulb the last 2 weeks of flower. Be sure to remove any glass from between the bulb and the plant as, like I mentioned earlier that glass is formulated to reduce UV.
On the buds closest to the 26w. Now you can actually "see" how far the effect is expressed in the increase of trich's. That's shows how effective the bulb is at growing distance from the bulb.
If you don't yet know. The plant is reacting to the UV by producing more trich's to protect it's self from the damaging UV radiation. This in turn raises the THC level simply because there are more trich's to carry it. The UV radiation ALSO increases the delta 9 THC content of the THC compound (delta 9 being the most psychoactive form of the compound).
While you can increase trich production with chemical manipulation. It appears that this way does not increase the delta 9 levels as much as the use of UVB! Yet, the increase in the total THC compounds by this method DO seem to increase the "relative"(the active relationship between the delta compounds) psychoactive effect!
So then. Once you try both methods, gather some test subjects and smoke one type against another on altering days. You will now have gathered data that should point to how well either way is effective to what your trying to achieve with one or the other.
To cover my size grow area with additional lighting for UV manipulation is not cost effective to the result. The use of MH for the last 2 weeks is cost effective in that there is no increase in overall electric use. Couple that with the chemical (nutrient) manipulation, it becomes interesting. The only problem at this point, again comes from the overall penetration of the UV effect to the lower budding on the plants. So now I have an inconsistency "problem"....Uniformity IS important to me and my Patients.....so then, this whole thing boils down to what YOU want to achieve!
All of this information is based on testing of the finished plant matter from differing locations on the plants. Both from "manipulated" and from "control" plants grown at the same time and both from the same mother.
The next thing I'm about to test is PAR lighting......730nm range lighting that runs at the end of the light cycle (20min before and extending to "about" 20min after lights out. We'll see how that goes. This is supposed to increase quality and yield!
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Vostok IS correct! Eye protection in and around the Merc lights, at the proximity you would be to them. USE EYE PROTECTION!