MIMedGrower
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@MIMedGrower I seem to recall the test you ran with hps and CMH. I'm not sure I can provide a specific reference that would satisfy your request. The one reference that comes to mind, I'm gonna have to find again. As I mention, and it seems we talked about this before - most of the published studies were not broadband light with a measured UV component, like we use in practice. On a cellular level, there are various receptors for specific wavelengths that do certain jobs, but only up to the UVA wavelengths. AFAIK, there are no UVB receptors. UVB does have effect, but the effect is damage control.
I notice no difference in the end product between the same plant grown with led or CMH. They were both just as flavorful, just as potent, and almost indistinguishable from one another.
However I did notice that LED gave me higher yield per watt and denser flowers. Also LED required less AC time to keep temps in range.
You would need the same watts to directly compare.
However,
A 315 cmh didnt make a percievable difference against my 600 hps in quality. But it did grow shorter, leafier plants with a lower yield.
However there are many tests that show up to a 4% increase in thc in lab tests against led and hps. And tests showing adding uvb the last two weeks shows the same thc increase as running uvb full cycle.
This is what the metal halide “finishing” 10k bulb was for.
I liked the buds best (and yield) with hps and cmh combined.
And i was only asking for a link proving what @weedtech stated.
While it is true I would need the same wattage to make an accurate comparison, but 265w vs 315w isnt much of a difference.
I'm sure tests of the extremes would show a 4% increase, but I bet you the average is much less. Compare good LEDs to crappy HID and the 4% might fully disappear.
Even if the 4% is a thing (I'm sure it is, I know you well enough to know you wouldn't just make that up) it's only an argument for supplementing UV in the last couple weeks of flower. Not HID the entire way.
Buying a uv bulb or two to run the last 2 weeks along side your LEDs would still give you the said 4%, less heat, less power and more gram per watt..
Unless I'm missing something crucial
Oh how I have missed this thread.... Not lol
FWIW.
Blue (~450–520 nm) and UV (< 400 nm) Light
Blue and UV-A light triggers cryptochrome (320–500 nm) and phototropin (phot1 and pho2; 320–500 nm) function (Jones, 2018). These two photoreceptors regulate various physiological and developmental processes including chloroplast relocation, germination, elongation, and stomatal opening, which impacts water transpiration and CO2 exchange (Cosgrove, 1981; Schwartz and Zeiger, 1984). Blue light mediates chlorophyll and chloroplast development, enzyme synthesis, and plant density, and regulates responses to biotic environmental stresses (Goins et al., 1997; Schuerger et al., 1997). Walters and Horton (1995) reported that blue light deficiency can impact the light saturation rate of photosynthesis and can change the Chl a/b ratio in Arabidopsis thaliana. Blue light causes thickness of the epidermis and palisade mesophyll cells in Betula pendula (Sæbø et al., 1995). Lee et al. (2014) concluded that shorter blue wavelengths (<445 nm) promote stem growth, plant height, and anthocyanin synthesis in green perilla (Perilla frutescens var. japonica Hara cv. Soim) plants. Cannabis plants grown under blue light with a short photoperiod (12 h light:12 h dark/flowering stage) improved cannabinoid content (Magagnini et al., 2018). This same study suggested that there is a synergy between UV-A and blue wavelengths that induces cannabigerol accumulation in cannabis flowers.
Blue light activates Zeitlupe (ZTL) family function, a group of proteins that plays a role in circadian clock regulation, wherein their light-dependent function allows modulation of internal timing signals (Kim et al., 2007). Accordingly, optimal lighting regimes for cannabis growth and production should take advantage of this temporal regulation initiated by the circadian clock and light-sensitive ZTL protein function.
Wavelengths of light that are shorter than the PAR spectrum [e.g., violet light and UV (<400 nm) radiation] have limited photosynthesis; however, discrete photomorphogenic effects are observed when UV-B (290–320 nm) sensing systems are triggered (Frohnmeyer and Staiger, 2003; Folta and Carvalho, 2015). UV-B radiation is perceived via the UV-B photoreceptor UV resistance locus 8 (UVR8). Although UV-B represents a threat to plant integrity in large quantities, smaller quantities of UV-B have important benefits such as promoting pest resistance, increasing flavonoid accumulation, improving photosynthetic efficiency, and serving as an indicator of direct sunlight and sunflecks (Ballaré et al., 2012; Wargent and Jordan, 2013; Zoratti et al., 2014; Moriconi et al., 2018). Further to this, some UV-B responses can also be modulated by a UVR8-independent signal and UV-A radiation, since plants’ responses to UV-B light are regulated by both UVR8-dependent and -independent pathways (Morales et al., 2013; Li et al., 2015; Jenkins, 2017). UV-B light reportedly elicits THC accumulation in both leaves and buds (Pate, 1983; Lydon et al., 1987; Potter and Duncombe, 2012).
Blue (~450–520 nm)......
And @MIMedGrower said let there be red and far red info. An there was red and far red infoSoon there will be new far red info to add.
Hi, I really like the color spectrum of cmh, and have thought about running 3-600watt in my 4x8 flowering tent. The only reason I haven’t, and my biggest issue with cmh, is that you can’t use them with air cooled ballasts, and I really didn’t want to add an ac unit to my tent. With air cooled hps my central air and exhaust and intake fans keep the temps perfect. I don’t know man, it’s such a big decision. Ya kno?!? Lol.LED lamps don't cover the UV spectrum, as presented by daylight. This is a (IMHO) gap that CMH lamps cover to better results.
Hi, I really like the color spectrum of cmh, and have thought about running 3-600watt in my 4x8 flowering tent. The only reason I haven’t, and my biggest issue with cmh, is that you can’t use them with air cooled ballasts, and I really didn’t want to add an ac unit to my tent. With air cooled hps my central air and exhaust and intake fans keep the temps perfect. I don’t know man, it’s such a big decision. Ya kno?!? Lol.
I call bullshit. Ain't no 300w light on the planet that will produce what 1000w can.If you are talking efficiency, no. You can replace a 1000w hps with a 300w led.
So in that case you can get 3 led lights for less of a power cost and have 3 times the light.
Don't pay attention to the advertises power consumption of led lights. Most of them use an equivalency rating. Something that is 1000w in advertising only actually draws 200w.
From what I've seen, leds can grow some great stuff. 1/4 the price on your power bill, less heat, more par for the $.
What's not to like?
I call bullshit. Ain't no 300w light on the planet that will produce what 1000w can.
I just wish all this "research" people throw into spectrum and LED lights would also carry over to actual growing, feeding, and nutes. "1st grow 3 days old.......XXXXXX HELP"
Lights are lights. Pick what ya like and go for it. It doesn't really need to be some 2 week journey of research. It ends up being about 10% of the equation of growing good plants. Why old ladies growing under floros with miracle grow and alaskan fish ferts kill it. Im not saying I don't enjoy the research and welcome it with open arms and pushing out the myths but please don't get so hyper focused on 1 thing when you are new. Specially when you have 1 to 2 lights in a tent. It's like arguing about which brand of nutes are better. People spend all this money and time on the lights and then can't even pop a seed, take a clone, or water a plant for a week without almost killing it.
Spends 600 bucks plus on LED's and talking about efficiency and spectrum.....doesnt buy a PH meter or know anything about it. Problems come up dumps Calmg into the plants. See?
By picking 1 diode or spectrum over another you arent going to leave a LB sitting on the table with under a 1000 watts of light. Lacking in the other depts can and will also tho.
God I have missed it also @Aqua Man :D
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I've been enjoying this discussion and will chime in briefly despite good points mentioned by most.
Been at this for over 35 years. We recently finished an 8 month test to figure out if our expansion will be fully LED. Tested many expensive units, and for the last 3 months of the test we also received 2 units that have yet to be released.
We're sticking with DE HPS. We were able to come very close with the LED solutions, but the top three were in the $1000-$1500 range after we had to add side lighting to match HPS yield quality. Density of the final product was a big deal, we were not able to match the DE HPS. Lack of UV was also an issue and it showed. Even with the almost-trivial power savings and not so trivial HVAC savings - the math still didn't make commercial sense.
My position is: If money is not an object, the high end LED units are a good option (600+ ACTUAL W). Especially in a warm climate and/or confined space. If you're out to grow the best buds possible, LEDs still have a few years to go - but they're a-comin'.
We ran our own tests because of what this thread demonstrates so well. Too many fan boys (on every side) and too little actual scientific method. We wanted to see for ourselves because we care about our money. We made our choice. For now.
Thanx for sharing ur experience.I've been enjoying this discussion and will chime in briefly despite good points mentioned by most.
Been at this for over 35 years. We recently finished an 8 month test to figure out if our expansion will be fully LED. Tested many expensive units, and for the last 3 months of the test we also received 2 units that have yet to be released.
We're sticking with DE HPS. We were able to come very close with the LED solutions, but the top three were in the $1000-$1500 range after we had to add side lighting to match HPS yield quality. Density of the final product was a big deal, we were not able to match the DE HPS. Lack of UV was also an issue and it showed. Even with the almost-trivial power savings and not so trivial HVAC savings - the math still didn't make commercial sense.
My position is: If money is not an object, the high end LED units are a good option (600+ ACTUAL W). Especially in a warm climate and/or confined space. If you're out to grow the best buds possible, LEDs still have a few years to go - but they're a-comin'.
We ran our own tests because of what this thread demonstrates so well. Too many fan boys (on every side) and too little actual scientific method. We wanted to see for ourselves because we care about our money. We made our choice. For now.
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