Bad News About LED vs HPS

[BobCajun]

This is very bad indeed

Yes, there was bad news after all, there's too much green in white light, you have to get 1/2 minus green filters. It sucks but what can you do? Fortunately they're reasonably priced and widely available. Turns out half minus green is just the right amount.

 

[BobCajun]

Illustration of the green and UV problems, from the article I quoted above. Now you might say but then why don't blue and red LEDs produce the same results. Well, you only need to remove half of the green from white light, not all of it. Some is good, too much is bad. Also the blue and red may be too narrow of bands. Maybe it's better spread out more like white LEDs.

 

[Johnny Lawrence]

Oh I don't know, maybe a little thing called look how bleached my plants are from those LEDs, brah. What up wit dat?

I run Area RWs to within 12 inches of the tops. I space 50 watt cobs out at about the same. You're trippin, bruh. What up wit dat?

 

[SoOLED]

LOL

 

[Rahz]

It's interesting for sure but best done on cannabis, and vegetative rate and flowering potential are different things. I hope you will post some info on your work with those filters.

The analysis I did on citi spectrums indicates 31.4% of flux in the 500-600nm range for 3000K 90CRI. That includes the 580-600nm flux that is not green, so the actual amount of green is probably around 25% (and no UV). The 2700K 90CRI SPD indicates 29% of flux in the 500-600nm range. 3500K 80CRI contains 37.3% of flux in the 500-600nm range and 3000K 80CRI contains 34.7% of flux in the 500-600nm range.

Take out the 580-600nm light and none of them are hitting more than a percent or so over 30% green. People have been testing these various SPDs for a couple years now and there's still confusion about which one is more efficacious for yield. The high CRI samples are in line with the ratios you're suggesting and while I am fairly convinced they provide better growth rates and finishing times, after several years of testing by various people it's still not clear if any of these spectrums produce better yield. Still, for those reasons I've been promoting 3000K 90CRI spectrum.

 

[Rahz]

I have the data in a spreadsheet so it was easy to isolate 500-580 %s.

3000K 90CRI: 26.8%
2700K 90CRI: 24.9%
3500K 80CRI: 32.2%
3000K 80CRI: 29.8%
3000K 70CRI: 31.9%

 

[mauricem00]

i realize youre in a closet but LED and HID (including HPS and CMH) all produce considerably less heat per unit of light produced relative to fluorescent.

as a persoanl med grower the 20-50% efficiency difference is likely irrelevant, few bucks a month

HPS does put out more LPW but CMH does not until you get into 1000 watt DE units.but the higher lumen rating for HPS is due to the spectrum they produce and not higher efficiency.one thing this study shows is that spectrum matters.lumens or ppfd tell you nothing about spectrum. one way of telling how much light your plants can use from a light source is to look at how much intensity is required to produce signs of light stress like photo inhibition and fox tailing.plants grown under my T5s look the same as plants I grow in my patio during the summer.in spite of the fact that LED grow light makers have been making false negative claims about fluorescent from the beginning they are still the best selling grow lights in the country and the ones recommended by horticulturalist,greenhouse and garden center operators http://www.littlegreenhouse.com/guide3.shtml I studied electrical engineering in the 70's and design and build my own drivers for the lights I build to test and learned about horticulture by reading studies and talking to horticulturalist at the local garden centers. like a gardener at the university once told me "I don't understand all these fancy theories. I need to let my plants tell me what they need" there Is a lot we don't know about plants so it still pays to learn to listen to them. I'm sure there are enough new growers with the spread of medical and recreational cannabis who are seduced by technology to keep LED grow light makers in business.but all the false claims being made by grow light makers is not helping their industry. in my area electricity cost 9cents/kWh. and I run a total of 600watts in my flowering and vegging closets combined so an expensive grow light would not last long enough to pay for itself. lumen depreciation is another factor these companies do not like to talk about. cree gives their COBs a 35000 hr L85 rating.about the same as energy miser bulbs and you would need water cooling to maintain the 25c operating temperature that rating is based on. if you had studies semiconductor physics you would know that it's heat and not operating current that causes semiconductors to degrade

 

[CobKits]

HPS does put out more LPW but CMH does not until you get into 1000 watt DE units.

i didnt say CMH > HPS
i said CMH > 85-90 lumen/W T5.

even with the 105 lm/W of a 315 bulb, its spectrum is so much better than HPS that many people yield a lb+ from 350W at the wall

T5s work great in the right hands
LEDs work great in the right hands
CMH and HPS all work great in the right hands
that doesnt change the fact that T5 is the least efficient out of all of them. yes the spectrum works well but its a small variable vs its efficiency which is the lowest of the pack by a significant margin.

cree gives their COBs a 35000 hr L85 rating.about the same as energy miser bulbs and you would need water cooling to maintain the 25c operating temperature that rating is based on.

more like >90% lumen rating at >61000 hours when run as high as 2100-2800 mA at 85-105C

for most growers using them at 1050-1400 mA at 40-70C thats probably closer to 100000 hours (25 years of 1212)

no manufacturer rates or tests chips at 25C (tho that info is sometimes provided). Ther is certainly no 'need' to run them so soft. you can blast them near their limits and still be as efficient as HID (and thus much more efficient than fluorescent)

 

[a mongo frog]

T5s look the same as plants I grow in my patio during the summer.in spite of the fact that LED grow light makers have been making false negative claims about fluorescent from the beginning they are still the best selling grow lights in the country and the ones recommended by horticulturalist,greenhouse and garden center operators

I think DE's are taking over in light assist greenhouse gardening, but yes T-5's are for sure the best selling veg lamps world wide. As shitty as they fucking are with bulb changes, they sell like hot cakes. All one would have to do is call any hydro shop in the world and ask them how many T-5s you sold this week? They are so far from being obsolete if so funny to hear people say that!!!!! I think they are pieces of shit and i own 10 of them.

 

[Rahz]

that doesnt change the fact that T5 is the least efficient out of all of them. yes the spectrum works well but its a small variable vs its efficiency which is the lowest of the pack by a significant margin.

Agreed.

l/w is based on both spectrum and efficiency but I don't think a spectrum for a white light will be much more or less than 4.5-5 umol/j and while that does make a difference it's on the order of a 10% difference at most. CFL just can't keep up, and 50%+ reflectance rate doesn't help. I've used both T5 and then cobs and the difference after the switch was so obvious and stark that I wouldn't recommend fluorescent to anyone. And that was T5 -vs- Vero gen5 at nominal current and what I believe was about 35% efficient by output.

 

[Hybridway]

Grow something side by side then talk about your results. Damn.

 

[nfhiggs]

HPS also has over 100,000 lumens, from one fixed source, It Punks the plant into making Buds, LOL.

It be Like,
" Fruit, You Bitch ass tree",

then, Bam, Buds...

Its a lumen bully is all.

LOL! Damn, I gotta admit, that made me laugh!

 

[BobCajun]

I have the data in a spreadsheet so it was easy to isolate 500-580 %s.

3000K 90CRI: 26.8%
2700K 90CRI: 24.9%
3500K 80CRI: 32.2%
3000K 80CRI: 29.8%
3000K 70CRI: 31.9%

Thanks, they do look low enough, at least the 90 cri, which may explain why LEDs at least appear to work better than HPS watt for watt. I'm pretty sure HPS has a lot more than that so maybe it really should be filtered.

The article said they adjusted the light distance to equalize the intensity for all colors of light, so it's not just straight filtering, it's more like filtering and increasing intensity to make it the same amount of light energy as before. It's still interesting how much visible difference it makes when the spectrum is lower in green though, even though using filters would waste power unless the difference in yield is more than 30%, since the 1/2 minus green filter only has a transmission of 71%. Here's a quote from the article.

Near-UV radiations were completely removed from white light with plastic filter with a low wavelength cut-off at 385 mp and 95 % transmission above 400 mu. The green component of white light was reduced approximately 50 % with a Cinemoid no. 36 pale lavender plastic filter. Appropriate adjustment of plant to lamp distance was made to equalize total radiant energy in Uw/cm2 received by the plants.

BTW you know how some light companies add near UV LEDs to make people think it will increase potency and they'll sell more lights? Well ironically it would probably reduce growth, unless Cannabis is immune to it, which is possible, at least at low levels. Doubtful it does any good though, and is certainly a health risk.

 

[ANC]

When you say the graph on the first post was at the same intensity, please tell me you used wattage drawn at the wall to the determine this. Or at least supply the details, you can withhold the names.

 

[BobCajun]

From the article I see that yields actually were increased by about 30%, so it might come out even. In this table the weights for the filtered lights are shown in percentages of the control, so 130 means 30% more than the control. I guess the image got downsized so it's a little hard to read. If it just works out even then probably not worth doing, though in the photo of the plants it looked like more than 30% bigger. Looked more like twice as big. Maybe it was mostly more stalk. Anyway I'll see how my filtered HPS works out. It's a lot easier on the eyes at least and the plants do look generally better.

 

[biostudent]

and again, green is beneficial. The plant needs the green to uptake CO2 better. Its the ONLY color of the spectrum that forces the plant to Utilize CO2 more efficiently.

I don't think that's true. The plant benefits from all the colours but not all are necessary even for CO2 uptake. CO2 uptake is regulated by stomatal contractions which is affected only by temperature and humidity afaik. Regardless of which color you provide, the end result is the same: electrons liberated from H2O are excited in the reaction center. The only difference between green light and any other is that green is responsible for fixation deeper within the tissue (where as blue fixes near the surface; red intermediate).

 

[churchhaze]

I think DE's are taking over in light assist greenhouse gardening, but yes T-5's are for sure the best selling veg lamps world wide. As shitty as they fucking are with bulb changes, they sell like hot cakes. All one would have to do is call any hydro shop in the world and ask them how many T-5s you sold this week? They are so far from being obsolete if so funny to hear people say that!!!!! I think they are pieces of shit and i own 10 of them.

You'd have to be You're pretty stubborn at this point to keep buying/using T5

 

[BobCajun]

I found the RGB percentages for HPS, way too much green. I gotta cut that in half thereby producing the "color corrected HPS", the newest thing in grow lights. Yes, it probably wastes power but then so does baking a pizza. It's a matter of priorities.

HPS has a set spectrum and the composition of the spectrum varies slightly between fixtures. However, the spectrum roughly contains 5 percent blue (400 to 500 nm), 53 percent green/yellow (500 to 600 nm) and 42 percent red (600 to 700 nm) (spectroradiometer scan on a 600W HPS lamp).

http://www.greenhousemag.com/article/luminous-possibilities/

 

[InTheValley]

I don't think that's true. The plant benefits from all the colours but not all are necessary even for CO2 uptake. CO2 uptake is regulated by stomatal contractions which is affected only by temperature and humidity afaik. Regardless of which color you provide, the end result is the same: electrons liberated from H2O are excited in the reaction center. The only difference between green light and any other is that green is responsible for fixation deeper within the tissue (where as blue fixes near the surface; red intermediate).

are we still talking about tomato plants?

 

[ANC]

One downside to green light is it causes stomata to close and reduce transpiration.