Sorry that I've taken so long to post, last few weeks I've had computer issues. While I was recuperating from an operation during the summer, I hooked up with a fellow that grows out mmj plant starts I provide to a nearby town's cancer group. He has a engineering back ground and we have had many talks about light, it's various spectrums and the effect on plants. He offered to do the work for a side by side UVb experiment, if I would guide him with the set up and provide the plant material. I've wanted to do the experiment that Rusty T talked about (see beginning of this thread), basically using UVb thru out vegative growth and then flowering.

The set up:

Built a box from 1/4" plywood, aprox 48"x30", divided into 3 sections of abt 16"x30". Each chamber would accomadate 1 greenhouse tray (abt 15"x24") that are designed to hold 15 pots that are 4 1/2" square and abt 6" high. These pots and trays are used commercially for flower and vegtable "starts" and make life easy by allowing a worker to move 15 plants at a time. BTW the trays are slotted to allow bottom feeding (ie ebb & flow).

All chambers used a 150w HPS that was mounted in a 4" pyrex (boroscilicate) glass tube that were air cooled. (poor man's cool tube using Bake a Round)
Chamber 1; was for the UVb veg & flower, so we used a 'Zilla desert 50 UVb CFL that is 20 watts. This was mounted in a small 6" diameter reflector next to the cool tube. Even tho this is a UVb bulb, it does put out a considerable amount of full spectrum light, and represents abt 15% additional light (by wattage) to the HPS bulb. So I felt I needed to add that additional light to the other chambers.
Chamber 2; was for controll, no UVb at all. So I added a 6500K 23 watt CFL, INSIDE the cool tube with the HPS. I did this to negate anything the CFL might put out to effect results. (boroscilicate glass does not pass UV light)
Chamber 3; was for no UVb during veg/ but UVb during flower. So for the veg time again a 23w CFL was added inside the cool tube, then when it came to flower it was removed and another 'Zilla 50 UVb was mounted outside the tube.

I used 5 differant strains in each chamber, 3 of each. The strains were: White Rhino, Shiva Skunk, Pure Power Plant, Cheese and "Apricot". This last one is a nick name I gave this strain because I recieved it as a cutting from a fellow in the midwest who was big on the use of apricot seeds for cancer treatment. It is a very interesting strain from the stand point of trichome production...it does not make any outside of the buds themselves, but seems to have a great deal of cannabinoids. It will increase appetite, curtail nausea from treatments and eases pain but does not have a real kick-ass high no matter how much you vape or smoke. Plus I have tried almost everything to see if I could get it more frosty but have had no success.

Grow medium was Pro-Mix BX, nutrients where Dutch Masters Gold using growth during veg stage and once into 12/12 used bloom. All chambers had the same tender loving care, and the enviroments where identical. Lights on temps where 78-80F and lights off abt 70-72F. No additional CO2 was used, just ambient levels, aprox 380 ppm. No other additional light sources were used (I usually use a far red source, but not this time).

This is getting long, so....next post will have our observations and findings.
Any questions abt the set up or experiment are welcomed and kibbitzing is encourged.