MasterWatererJeff said:

Sativa strains need uvb. Oh excuse me "equatorial varietals"

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All you need is UVA.

Blastfact said:

All you need is UVA.

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Tell us why

I use Solacure from Seedlings - late flowering. The last 10 days I turn it off.
I use 2 x Flower Power bulbs per 1x 1000w Hortilux HPS bulb in a 4 x 4 area. I use them 4 hours a day from seedling to finish at about 20- 24 inches from the canopy.
I figure plants get UV from seedlings- flowering outside, so why not inside??? Plus there is no breakin period when introduced in flowering. You can easily fry them if they are not broken in to the UV. About 5% of the suns wavelength is UVB. 95% is UVA, so the earth does get UVB. UVA/B is highesst at the equator, and even higher at the equator in the Andes mountains. Equador has an extremely high amount of UVA/B , and even higher in the mountains. Even at sea level in Equador the UVA/B levels are dangerous to humans.
I also run my HPS/Hortilux 1000w at 24 hours a day in veg, an turn them off for 3 hours every 3 days to give them a slight rest.
When I use a DE Gavita 1150w with a Hortilux HPS DE Bulb I have them at 48 inches from the canopy, and run them 8 hours a day because they are so far away, and I use 4 f them in a 6 x 5 area. The Hortilux DE HPS bulb is 2400umol vs 2100umol for the Gavita bulb. But to use this much light you must have alot of fresh air exchange, or CO2, and also may have to have a way to cool the room. It takes about 4000 BTU to cool 1 1150w DE light. And they have an extreme amount of Infared.

use it at week 4 of flower to harvest !!! other than that it's off

shaganja said:

Tell us why

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UVC is deadly. Most of the UVB the sun produces is filtered out by our atmosphere and fails quickly when reproduced with leds, hids or fluorescents. UVA is safer with UVA leds, hids and floresecents lasting much longer. Remember UV is not easy for man to reproduced in a reliable, cost effective manor. Most of what plants outdoor are really exposed to is UVA which has a longer wavelength thus it penetrates deeper into plant matter over longer exposure time. Strains from mountains, steps and equator all respond good to UVA and some B with B not being necessary. It's in the plants gentic code of survival. Mostly indicas with a spattering of sativa from the equator region. Thats why all the plants used in these areas of the world are the good hash and extract producers. UV basically makes the plant produced more sunscreen in the way of trichomes and resin "IF" the plant has the genetics to do so. It does not make the plant more potent, just more of what it has. A lot of this crap, hybrid, fufu weed we have now days does not respond to UV at any level and much of our current crap weed can be hurt by UV. With the longer wavelength UVA has and if the plants can handle it,,,,, it's great for growing in thick trained canopy's and untrained natural grows. Last grow I used UVB on was a landstrain/bag seed Colombian Gold Plant from 1975 I collected myself in the days when we still had real weed. That plant was in flower better than 20 weeks. I had access to a spectrum analyzer back then that we used in a UV light test for use of UV in hospitals, lab and air/surface purification testing. I went through 8ea. T5 bulbs from several manufactures and one ballast just to flower that plant under no more than 2 hours a day of UVB. You could see daily how the UVB bulbs output was deteriorating daily every time the light came on. Output became less and less everyday. Now for those that have the coin or are willing to spend the grip on say a Apogee 610 ePar class meter the meter will show the UV in PPFD. While Apogee says it's not for UV measurement they damn sure do show it. And you can watch UVB drop in total PPFD when using any brand T5 HO UVB at a claimed 24/25 watt. Reality is most only draw 20 watt to 15 watt and that goes down as UV production goes down which can be seen with a Kill-A-Watt, Amp Probe or tool of your choice and calculations. I have UVA in my two tents and use it when I can. Or should I say when the plants can use it. And seeing grows from the last two years or so have been in large part tester grows for a buddy who thinks everything should be a crossed, bred up low IQ fufu weed most have not responded to UV at all. Which on one hand is great meaning I haven't used my UVA lights much so there still fresh and outputing good UVA so when the landstrains and real weed seeds start showing up from a buddy on a landstrain hunt I will be ready to grow.

This is what Dr. Bugbee says about UV

We have NOT found that supplementing with either UVA or UVB increase cannabinoid synthesis.

Supplemental UVB is highly damaging and can decrease photosynthesis and yield, however.
We are continuing to study this.

hawkman said:

use it at week 4 of flower to harvest !!! other than that it's off

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I run mine 12 hrs a day from flip to finish.

shaganja said:

Tell us why

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From personal experience the plants finish faster. This is a photo period plant after 49 days from flip under a UVA that is on 12 hrs a day since flipping to flower. I have observed this accelerated finishing in every grow I have done under this UVA bar.