Spectrum Advice

NM High Desert

NM High Desert

Active Member
First, thanks to all who have unknowingly contributed to my first DIY LED build.
This is also my first grow. I turned on my new lights 2 weeks ago and my girls are so happy!

I replaced my t5 VHO lights with 15 CXB3590 3500K, powered by 3 HLG-185H-C1400B drivers covering a 4 x 5 area.
I am adding 8-10 more 3590s to fill in the spread but I want to add a spectrum to aid in bud quality.
This is a personal medical grow so I am interested in quality over quantity.

Thanks in advance for your input.
 
Rahz

Rahz

Well-Known Member
If you add 3000K cobs it will lower the overall K to around 3300 or so.

Changing the average K value is all it will accomplish. I think anything in the 3000-3500K is going to be nice. No scientific evidence high K ratings increase THC content that I'm aware of. You might play around with using low levels of UVB but I'm not sure there's any scientific evidence to support that either. I've looked around and it seems low latitude and high elevation corresponds with higher THC production, but that's not good science IMO. I've seen anecdotal data suggesting UVB lowered THC from a grow using the same cut, such as this snip: "I have been doing GC/MS for over a year now. I got an 18%THC off a cut with high UVB/ 400-470nm and 27% THC off the same cut with almost no UVB at all under mostly standard HPS." so some serious testing is needed to convince me the benefit is real and if so reveal what level is helpful and what is harmful.

If there is solid data to support UVB I would be interested in checking it out. I haven't scoured the internet so it's possible someone has done some definitive tests. If so perhaps this thread could be used to further awareness of it.

I think beyond genetics there are a variety of factors including the light, nutrients, canopy temps, O2 and CO2 levels, root environment, etc. that will push a plant to it's potential. It's possible to provide a sub par spectrum, but these full spectrum cobs in the 3000-3500K range correspond very closely with the Mcree curve. Improving the light from there is mostly increasing the PPFD IMO. More photons!
 
testiclees

testiclees

Well-Known Member
Rahz said:
If you add 3000K cobs it will lower the overall K to around 3300 or so.

Changing the average K value is all it will accomplish. I think anything in the 3000-3500K is going to be nice. No scientific evidence high K ratings increase THC content that I'm aware of. You might play around with using low levels of UVB but I'm not sure there's any scientific evidence to support that either. I've looked around and it seems low latitude and high elevation corresponds with higher THC production, but that's not good science IMO. I've seen anecdotal data suggesting UVB lowered THC from a grow using the same cut, such as this snip: "I have been doing GC/MS for over a year now. I got an 18%THC off a cut with high UVB/ 400-470nm and 27% THC off the same cut with almost no UVB at all under mostly standard HPS." so some serious testing is needed to convince me the benefit is real and if so reveal what level is helpful and what is harmful.

If there is solid data to support UVB I would be interested in checking it out. I haven't scoured the internet so it's possible someone has done some definitive tests. If so perhaps this thread could be used to further awareness of it.

I think beyond genetics there are a variety of factors including the light, nutrients, canopy temps, O2 and CO2 levels, root environment, etc. that will push a plant to it's potential. It's possible to provide a sub par spectrum, but these full spectrum cobs in the 3000-3500K range correspond very closely with the Mcree curve. Improving the light from there is mostly increasing the PPFD IMO. More photons!
Click to expand...
Any first hand experience testing the effect of UVB exposure?
 
Rahz

Rahz

Well-Known Member
No first hand experience.

I am interested in hearing about any side by sides using the same cuts. That type of testing does have scientific validity but the fact that others have done small tests and not shown improvement means some larger scale testing is in order, along with various levels of UVB to figure out what the limits are.
 
kachiga

kachiga

Well-Known Member
Rahz said:
No first hand experience.

I am interested in hearing about any side by sides using the same cuts. That type of testing does have scientific validity but the fact that others have done small tests and not shown improvement means some larger scale testing is in order, along with various levels of UVB to figure out what the limits are.
Click to expand...

That's a cool idea. I have uvb bulbs and I have never grown the same strain twice so I can not tell you there. But I can say I do notice a differnce. Again it not the same strain, but that thing was oozing (ghost train haze). I have grown same lights not used it and noticed.

Again not with the same cut let alone same strain.
 
BOBBY_G

BOBBY_G

Well-Known Member
NM High Desert said:
First, thanks to all who have unknowingly contributed to my first DIY LED build.
This is also my first grow. I turned on my new lights 2 weeks ago and my girls are so happy!

I replaced my t5 VHO lights with 15 CXB3590 3500K, powered by 3 HLG-185H-C1400B drivers covering a 4 x 5 area.
I am adding 8-10 more 3590s to fill in the spread but I want to add a spectrum to aid in bud quality.
This is a personal medical grow so I am interested in quality over quantity.

Thanks in advance for your input.
Click to expand...
t5
use a 6500k to throw more light and stack them down in early flowering, throw in a 2700 k or high uv bulb for last half of flowering
 
BOBBY_G

BOBBY_G

Well-Known Member
Rahz said:
No first hand experience.

I am interested in hearing about any side by sides using the same cuts. That type of testing does have scientific validity but the fact that others have done small tests and not shown improvement means some larger scale testing is in order, along with various levels of UVB to figure out what the limits are.
Click to expand...
this doesnt push the limits but shows some positive correlation

https://silassativarius.org/2014/10/03/does-exposing-your-plants-to-uvb-increase-thc-production/
 
NM High Desert

NM High Desert

Active Member
Thanks all for freely sharing your hard earned knowledge.
I am still taking baby steps but my learning curve is steep and all of you have helped make my life easier.
 
C

churchhaze

Well-Known Member
Consider this... I've been hearing about how UV-B increases THC since I started growing. (over 15 years ago). The question still remains... Somehow it's not definitive science after all that time.. It makes me skeptical if it's worth any of my time.

I've always been under the assumption that UV-B damages plants and that's all it's good for. (ionizing radiation)
 
sixstring2112

sixstring2112

Well-Known Member
interesting link from the link bobby g gave.you need to use the uv lights from seedlings to see an increase,hmm. the first link reads like a cali lightworks add to me but this one seems legit http://medicalmarijuanagrowing.blogspot.com/2013/02/uvb-uva-lighting-study-results.html
it also talks about the lamps needingto be close to the plants,and/or the sides and bottoms dont test higher at all.so in theory you will need uva/b lamps on top and both sides of larger plants like mine or you will have strong top colas and normal buds everywhere else.makes sense to me because these types of bulbs dont have penetration power.but it basically says if you use them in bloom only they see no real increase in potency.
 
testiclees

testiclees

Well-Known Member
churchhaze said:
Consider this... I've been hearing about how UV-B increases THC since I started growing. (over 15 years ago). The question still remains... Somehow it's not definitive science after all that time.. It makes me skeptical if it's worth any of my time.

I've always been under the assumption that UV-B damages plants and that's all it's good for. (ionizing radiation)
Click to expand...

However, UV-B is not solely an agent of damage and has an important role as a regulatory signal. In particular, the perception of low levels of UV-B by plants actively promotes survival because it stimulates responses that help to protect against and repair UV-damage. Plants are unavoidably exposed to UV-B because they need to capture sunlight for photosynthesis. The fact that plants rarely display signs of UV-damage in the natural environment demonstrates that they have evolved very effective mechanisms for UV-protection and repair. The protective mechanisms include the deposition of UV-absorbing phenolic compounds in the outer epidermal tissues and the production of anti-oxidant systems. Repair of UV-damage involves enzymes such as DNA photolyases. Furthermore, responses to UV-B modify the biochemical composition of plants, influence plant morphology and help to deter pests and pathogens. It is well established that many plant responses to UV-B involve the regulation of gene expression. UV-B exposure stimulates the expression of hundreds of genes, including those involved in UV-protection and repair.

http://www.gla.ac.uk/researchinstitutes/biology/staff/garethjenkins/researchinterests/plantresponsestouv-8/
 
testiclees

testiclees

Well-Known Member
http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.1998.tb09689.x/abstract

The use of genetically modified plants offers unique opportunities to study the role of specific flavonoids in plant UVB protection. Along with a parental wild-type MitchellPetunia, two transgenic lines with altered flavonoids were also examined; Lc with enhanced levels of antho-cyanins due to the action of a maize flavonoid regulatory geneLeaf color, and AFLS that carries an antisense fla-vonol synthase construct and is known to have reduced flavonol levels in flowers. All three lines were grown in near ambient sunlight, sunlight lacking UVB (280–320 nm) radiation and sunlight with 25% added UVB. Ultra-violet-B radiation induced significant reductions in the rates of leaf expansion and seedling growth in all three lines. The presence of anthocyanins did not appear to afford Lc plants any special protection from UVB. Ul-traviolet-B treatment induced increases in total flavonol content in young plants of all three lines, and this effect decreased with increasing leaf age. Notably, increasing UVB levels led to an increase in the ratio of quercetin: kaempferol with all three cultivars. The AFLS transgenic, contrary to expectations based on its genetic construction, had normal levels of flavonols in the leaves and the highest Q:K ratio of the three cultivars. This transgenic was the least susceptible to UVB, which may indicate an enhanced protective role for quercetin. Because both quercetin and kaempferol have similar UVB screening properties, quercetin may exert this role by other means.
 
testiclees

testiclees

Well-Known Member
http://www.sciencedirect.com/science/article/pii/S014765130900030X

The effect of supplemental UV-B radiation (sUV-B) was evaluated on the essential oil contents of sweet flag (Acorus calamus L.), a medicinal plant grown under natural field conditions. After the emergence of two leaves, plants were exposed to sUV-B radiation of 1.8 kJ m−2 above the ambient level of UV-B. The level of essential oil and phenol contents increased with exposure to sUV-B. Exposure of sUV-B resulted in significant increase in p-cymene and carvacrol contents of essential oil. Decrease in the level of major component beta-asarone due to sUV-B treatment is of prime importance, because of its toxicological concern to human health.
 
BobCajun

BobCajun

Well-Known Member
sixstring2112 said:
but it basically says if you use them in bloom only they see no real increase in potency.
Click to expand...
You probably meant this; "it does not make any difference to the potency if you use the lights in bloom only." It was just bad wording. He meant it was the same increase in potency if used only in bloom as if used the whole growth period. In fact, it's the same if used only the last 2 weeks and maybe even 1 week as if used for the whole flowering cycle or whole veg and flower cycle.

I'm trying the reptile CFLs now, 26w Exo Terra 150. I tried them at a fair distance and not much difference so I dropped them down to about 6" away. After one cycle of that they looked undamaged. Since you need an aluminum reflector over them the main light does get shaded in that spot but the 150 rep light does have considerable PAR light in it so presumably that will make up for the shading of the main light. If they weren't so costly I would just use all rep CFLs as grow lights for the last 2 weeks.
 
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