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Thread: UVB/Cannabis science report

  1. #11

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    tetra are you doing or going to do a test grow?
    will follow with much interest.........go on go on.

  2. #12

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    Quote Originally Posted by wert View Post
    tetra are you doing or going to do a test grow?
    will follow with much interest.........go on go on.
    In my present grow i have a 13w repti glo with perfect uv spectrum as supplement to my 250w hps. Thats allrite for my small space. Will not boost as much as possible but i think it will make a differance. 4.7 kJ i think it measures, and to get 15% extra thc in trichomes one needs 6.4 kJ, so maybe i reach 10% if i estimated correct. But thats nice also A friend of mine is running 60w repti glo 10.0 flat tubes. Mine is a compact cfl type. He claims to get great results and extra sugar on his plants. He last grow Big Bud under these lights, and said he got some wicked weed out of that, more potent than previous grows of same strain. I dont think there will be so much extra trichs with UV supplemental lights anyway, the magic happens inside the trichome glands, where THC is elevated to sheild out the UV light.
    Last edited by Tetra; 10-02-09 at 10:45 PM.

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  4. #13

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    i was thinking along the lines of a test grow where you up the uv till we find when the plant grows at its best with the uv input and when it goes over and has a detrimental effect on the plant.
    are there any side effects to useing uv less/more vigorous growth of foliage?
    does too much stress the plant?
    it's an interesting subject.

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  6. #14

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    No, but i'd be happy to see such a test performed. I'm not planning to grow in a while after this harvest, due to not so good circomstances right now for growing safe. But, i think the scientists have done a pretty good job at researching about this subject. 13 kJ / sq.m produces a sinificant rise in THC levels, as far as 32% increase. Thats enough alone, but maybe they could be stressed to produce even more. No, plants show no significant harm to this requency of UVB light (280-315 nm), however if using wrong UV wavelength wich not is absorbed by THC there may be some harming effects. I have had my UV light on the whole growth, to give em a bit of UV stress from the beginning so they concentrate on producing glands. I think maybe to much UV can stress the plant and make harm, because it's reasonable it is limits on how much UV the THC can absorb. But maybe that would have some triggering effects causing the plant to accumulate more trichome glands. In this safe amount the scientists used they did not see more trichome production, just higher levels of THC in the glands.

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    To be absolutely sure to get best results then use the same types of bulbs scientists used: Westinghouse FS-40 Sunlamps. They filtered them out to only radiate exactly 300 nm UV-B light using: Presolarized 0,08 or 0,013 mm cellulose acetate (UV-B transmitting) or 0,13 mm Mylar type S (Control) filters. But personally i think it would work well with a suitable UV-B lamp from zoo shop with right specrum properties like the Repti Glo 10.0.

  9. #16

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    good job Tetra... very exciting stuff. Can't wait for someone to check this out on their grow.
    .
    First grow
    250W CFL stealth hempy. Jock Horror.
    Second grow 375W CFL stealth hempy. Early Girl.

  10. #17

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    I have been using uvb bulbs since reading up on uvb and some old threads on other forums, filled my head with all sorts of uvb info I would be happy to share.

    MH for example do emit more UVB than HPS (which produce almost none usually) but particularly more UVA, though the glass of the bulb itself blocks UVB. Having said that, some MH tested did have significantly high UVB, even within same brand, depending where made and type of glass used., some used MH bulbs with the glass shielding removed to remove that obtacle but that is FAR from safe and I strongly advise against it.

    There seems little doubt from what I have read from various sources that UVB is utilized by the plant in that the trichomes produce more of the THC, either within the trichome or the plant may produce more of them.

    Its important to note the safety aspect of UVB bulbs though and treat them like they are radioactive, 100% UV blocking safety glasses (wrap around to cover sides of eyes preferably) are essential though best you are never even present when they are on, its far from good for bare skin either.

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    Well, i knew MH radiates UV, but it has to be in the right frequency, around 300 nm wavelength (UVA is higher frequency). And at 13.4 kJ / m2, i think that converted to W is around 72w / m2 of pure UV, to get the maxiumum effect of 30% rise in thc production in flowers. So I see a made a miss calculation, and 3x26w Repti glo 10.0 should be perfect. I remembered wrong in first post, the repti glo's come in 13w and 26w cfl's.

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    Quote Originally Posted by wert View Post
    i was thinking along the lines of a test grow where you up the uv till we find when the plant grows at its best with the uv input and when it goes over and has a detrimental effect on the plant.
    are there any side effects to useing uv less/more vigorous growth of foliage?
    does too much stress the plant?
    it's an interesting subject.
    The consensus of opinion after trials was that UVB used supplementally for 15mins - 4 hours, depending on the output of the bulb used mid way between the 12/12 cycle as thats when the suns UVB is highest in nature was the best way to go. Distance from plants is essetial though as the bulbs emit more when new and then increase again as they get old. There was some debate on whether using during veg might prepare the plant for it and affect its development in preparedness. Also a test grow was done with just a uvb bulb long ago and it grew fairly well but too much UVB or too strong/close can cause sunburn effects on plants and even mutations, as it can with lizards,when using these lights (or anything living) so should be treated with healthy respect.

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  16. #20

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    Quote Originally Posted by Tetrahydrocanna View Post
    Well, i knew MH radiates UV, but it has to be in the right frequency, around 300 nm wavelength (UVA is higher frequency). And at 13.4 kJ / m2, i think that converted to W is around 72w / m2 of pure UV, to get the maxiumum effect of 30% rise in thc production in flowers. So I see a made a miss calculation, and 3x26w Repti glo 10.0 should be perfect. I remembered wrong in first post, the repti glo's come in 13w and 26w cfl's.
    Thats the ones I ended up with, the 26w, you have to be careful when using a reflector if you do use UVB bulbs as some materials reflect 100% and can create a hotspot of intense UVB. The wavelength of those lamps covers the ranges needed, though as with all CFLs the penetration at useable ranges is limited, means they work especially well with LST grows though

    The UVB from MH bulbs that did emit some it was only at very close distance to the bulb and unless using cooltubes unlikely to be utilized by indoor grown plants from what I could tell, irrespective of frequency.
    Last edited by Nephilim; 11-02-09 at 04:19 PM.

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