Quick background: I have been using UVb supplemental lighting for many years now and have always thought it added to the finished product in a couple of ways. I had never promoted it's use on these boards because I felt it was dangerous and had real potential to harm people. That changed a few months back on the other UVb thread, and I came out of the closet in strong support of it's use. Well some here who's opinion I respect (like Weezard) held the opposite view and those discussions led me to the fact I had not done any experiments in a long time trying to compare it's effects.

So I decided to do back to back runs, with and without and to try to see, observe and quantify the differences. I decided to use my personal grow to do this since it is well dialed in and consistent, and I have been using UVb as supplemental lighting. The other grow I'm involved in, I could not seperate some UVb in the bloom room cause of it being built into some lights, like the TI problooms.

Strain is WhiteRhino, grown as SOG size plants (finish @ abt 18" tall) in 4" RW delta blocks in a GI Grow rotating garden. The light source is a homemade LED/T5 hybred; the LEDs consist of 240 red (635nm) Cree's driven at 650ma giving 1.75w/ea for a total of 420 watts and 8 2700K 2' T5s overdriven to VHO levels of 40w/ea for a total of 320 watts. All together it's 740 watts of light, plus power supplies and fluro ballasts. All of this is mounted on a 4" octogon aluminum extrusion and mounted inside a 6" boroscilicate glass tube that is ducted for air cooling. There should be no UVb transmitted thru the glass, if there is any from the T5s.

I started this last run with out UVb on June 7th (full moon) and today marks the 7th week (lost 2 grow days to power outage) they have been in flower.

Early observation:

1) I have always claimed that UVb adds to trichome production, but I have not seen a difference w/o UVb. The WR packed on the tric's just like before, much like white strains do, tric's solid on buds and leaves, some trying to grow on top of each other, often thought it was UVb but it's not. Based on this, and something I've seen in the other grow I must admit trichome production is more a product of genetic predisposition then UVb light influence. My first sorta surprise.

2) Second surprise (big one) is the leaves of the plant in this run are paper thin in comparison to previous runs. W/ UVb the leaves are much fatter and tougher, a very noticable difference. I don't recall reading anything about this, but it looks like UVb adds to the overall plant mass.

3) At this point of 7wks, I would expect to see trichome's that where clear with maybe 25% turning cloudy. Tric's are currently all clear, did lose 2 days so maybe that's the difference, not sure at this time.

So that's where I'm at right now, everyone is welcome to hang out while I wait and see what happens over the last week or so and I get to final finish and a taste test. Question or comments on or off topic are always welcomed even encouraged.

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oldmac Reviewed by oldmac on . UVb an experiment Quick background: I have been using UVb supplemental lighting for many years now and have always thought it added to the finished product in a couple of ways. I had never promoted it's use on these boards because I felt it was dangerous and had real potential to harm people. That changed a few months back on the other UVb thread, and I came out of the closet in strong support of it's use. Well some here who's opinion I respect (like Weezard) held the opposite view and those discussions led me Rating: 5