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New Grow room Lights

Okay I did go and do some more reading... according to Ed Rosenthal in his book Marijuana Growers Guide pg 357 under the heading "BLUE LIGHT" he states that during flower the plant is very sensitive to red light, and any interruption in the lighting period with 660 nm returns the Pr back to its inactive state. However Blue Light at 400-450 nm has an inhibitory effect on flowering, and if such a light were to be left on during the DARK PERIOD the plants would continue to grow vegetatively as well. They would produce enough flowers for sexing, but not go into full flowering mode.

I would look back to see when I added the light, what my lighting schedule was, etc... but I no longer have that... but believe me I will take your theories and I am keeping track of them to evaluate this more in the future... One way or another I hope to solve the riddle of why it worked that way.
 
Any light other than monochromatic green during the DARK PERIOD will prevent or stop flowering. This is because phytochromes are not exclusive for red light absorption only, they also respond to blue light as well.

pchromespecs.gif


Michigan university conducted some pretty interesting studys on the effects of strong blue light on flowering during the LIGHT PERIOD. What they found was that blue slowed down the flowering in short day plants and the opposite for long day plants.
Using red or blue light during the dark phase will cancel any effects from flower initiation. Plants measure the DARK PERIOD from when phytochromes ratio is converted during the light period to when they are reconverted again after the dark period. They do not measure the light period and do not function on a concept of hormone concentration for the initiation process. Once the flower process has started, chain reactions occur which make it diffucult to stop. This is why it takes a while for a plant to convert back to veg.
 
I had a quick, however i wont go into to much detail.

They are correct in their understanding on the technology (mostly), but how and what they believe is applicable to plant growth is not correct. I think this happens often with grow light companys. They fail to understand plant biology and incorrectly design grow lights because of such. Even spectrum king uses very inaccurate and poor technical terms for advertising their products technology. Using such terms as "white light is more efficient" is either plain bad understanding or just misleading advertising. White light must be derived from blue LEDS with phosphor coating or from combined assorted LED colors. Although it has higher efficacy (efficacy means the conversion of energy to the desired result) for lumens. It is less efficient because it must be derived from blue or other colors, it cannot be more efficient than the colors from which it is being created from. Meaning although white has higher lumens per watt, its actually less efficient in converting energy to light because lumens is a measure of photometry and is useless for realizing with plant biology.

Now CMH are more efficient and produce less heat compared to MH, however a lot of that light falls outside of a plants photosynthetically active range. Meaning wasted light. Its efficacy for grow lights is about the same but usually less compared to metal halide. Compared to HPS they are not better.

This has been shown with successive studys comparing technologies. Greenhouse studys show LED and other technologies to be less efficient both electrically and cost wise to be used as indoor or supplimental lighting.
 
Can you give me some links to the study's (you referenced)... I love reading up on this stuff.. Thanks. The more I know, the better grower I hope to one day be.
 
It seems i miss some replies and dont seem to show in my notifications. My applogies for this late reply. I only manage to stumble upon these missed messages when i am back tracking old posts.

Here is a study on greenhouse analysis with supplimental lighting. Wrong interpretation of the material might be misleading or difficult, so if you have any questions feel free to ask. However maybe a PM at this point would suffice.

Study click here
 
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Danofdanger Hello ! I found all the info you have provided well thought out and fascinating. You wrote it so a layman can understand your logic and reasoning. The link you provided is now dead and I'm contemplating buying 630W DE CMH fixtures. What I thought I understood about them and their light spectrum was basically what you've written relating to MH and HPS but mention CMH lacks. Do you 6 months later feel MH and HPS is superior in the spectrum of light available from the CMH DE 630 W ?
 
I could not find any convincing data to suggest the superiority of CMH. Although the price has gone down, it still does not ouperform high pressure sodium. For it to be a economic advantage, it would need to be either cheaper or efficient. So its hard to justify any reason to choose over its counterpart.

All the data i could find that asseses CMH showed no advantage over HPS. Although not entirely scientific, i do respect the data aquired by monster garden. They have the best forward thinking test parameters. They have tested dozens of lights and differing light technologies using methods that are acceptable by my standards. They did not compare HPS directly so the only reliable comparison was with metal halide. But they showed that CMH was only slightly more efficient, with a particular brand of metal halide actually outperforming it. Now its undisputed that HPS is more effective and efficient than MH. So if we take that information as correct, we can assume HPS is more efficient. Another study from utah other than the one i provided also showed HPS as being more efficient. Not by much however. There are even a couple more tests not worth mentioning that showed much the same.

With regards to the light quality, there is actually a disadvantage for the particular type of spectrum that CMH uses. If we go by the mccree curve, which is now out of date and recent studys show to be incomplete. We can see that the higher blue and green percentage is less efficient based on the quantum efficiency provided by mccree. So the upper hand would be given to HPS due to most of its energy being distributed closer to the red part of the spectrum. However as i stated, the mccree curve is not current anymore. This is because of incomplete data. New data shows that at high radiant intensity, the quantum yield begins to be more linear accross the spectrum. Meaning light quality is of less importance compared to light quantity. This is mentioned in the paper i provided.
However light quality does impact plants morphology, with something called photomorpogenesis. The current studys on this have clearly showed the morphological differences between the light bandwidths. However to satisfy each response only requires a small portion of the total capacity. I refer you to my other post #6.5 in this thread on that subject.

I could not find any information suggesting the improved efficiency of the technology of the last two years. Ceramic metal halide is not a new tech. Its been around for 30 years and has merely just been rediscovered for the growing industry.
I tried my best to find anything to suggest CMH as being better, but all i could find was the subjective opinions from people who have them. Which must be taken with a grain of salt, there are so many variables such as genetics, environment, reflectors, height, growing parameters etc. Its just not reliable.

You let me know if you have any information.
 
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Thanks Danofdanger, if only they all delivered what they promised. I am thinking that the advantages of MH/HPS would in my application be offset by the need for Air Conditioning to lower ambient temperature in the room below 80's. The figures for Photon efficiency on the 315W CMH were 146 compared to the industry standard 1000w Gravita MH/HPS which was 170 per µmol/s. For the amount of watts used 315 Watts vs over 1000 Watts not a huge effiency difference and very respectable with operating costs for power consumed for light and cooling figured in. I can only postulate these numbers will improve with new data concerning the 630 W Double Ended CMH Low RF technology being marketed now as compared to single ended lamps and higher frequency RF Ballasts of 2014. Quality not quantity aside 3 times 630W DE CMH @ less than $750 vs one Gravita 1000W DE MH/HPS for $425, Ceramic seems the best quality and quantity for the investment and operating costs. I don't really know it just seems that way to me regarding all the different variables.
 
The photon efficiency is calculated by the photon output, devided by the power (watts) input. So comparing the wattage usage like you did is contradicting the value your represented. In other words.

315w CMH is 491umols ÷ 337w = 1.46 (the extra power consumption comes from heat loss from the ballast)

To take the equivalent photon efficiency from DE Gavita and create a theoreticle comparison we would get something like this.

315w HPS is 575umols ÷ 337w = 1.7 (extra power loss also added)

Thats roughly 30 watt difference. Not huge. But the difference gets to nearly 100 watts when you reach around 1000 watts input.

Digital (square wave) ballasts have been around for years now, nothing new and low frequency is a requirement for the cmh bulb technology. Not a improvement aspect. Older and some current digital ballasts, are still low frequency. The new high frequency ballasts were introduced to combat resonance in HPS bulbs that in some cases caused premature failure. The frequency however has no effect on output efficiency. Any efficiency improvements comes from reduced heat loss from switching circuits in digital ballasts (mere watts). Ultimately the effciency is dictated by the bulb.

As far as heat dissipation, thats another one that i have not tackled yet. The bulb does produce less heat, because of its higher efficiency. But a lot of that light falls outside the PAR range. Which means it goes wasted and turns back into, you guessed it. HEAT!.
Although the heat is not concentrated around the bulb, but spread out some by the environment. So i would bet that there would be very little difference of energy in the form of heat being produced. But im just speculating now.
 
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As i stipulated below, there are no advantages i can see over HPS. Perhaps a great replacement for metal halide. But not HPS. Another reason that suggests CMH is inferior, is that most bulb manufacturers claim the luminosity far less than HPS. Luminosity is based on the human eye response which is heavily concentrated in the center of the spectrum. CMH should at least be close if it were more efficient. Especially since more energy is produced in this midband area, producing that white light response. But its not.

If i had the chance to do my lighting system over, i would still choose HPS, even single ended. Hands Down. My next investment will be LED when it starts to become more economically viable.
 
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