All light outside the peaks at ~450nm and ~650nm (blue and red) is of little use to plants, photosynthetically speaking, and is therefore wasted energy.
This is a common myth, with the sellers of plant lights only too happy to let it run. All light in the visible spectrum, and a considerable amount outside it, is of use to plants. Chlorophyll itself absorbs most strongly at the wavelengths you mention, but also at other wavelengths. A single chloroplast absorbs green light quite inefficiently, but a leaf or cactus doesn't just contain one chloroplast, so a considerable amount of green light is also absorbed. "Chlorophyll" is actually multiple related pigments, with the two dominant forms absorbing light strongly over the whole of the ranges at 400-500nm and 600-700nm. In addition there are other pigments that absorb light at different wavelengths from chlorophyll and transfer it into the photosynthetic pathway. Not all of this energy goes into photosynthesis, but some to other synthesis or regulatory functions. The total conversion efficiency of whole leaves ranges from well over 90% at its peak in the red and blue, to around 20-60% at its lowest, depending on the particular plant. Perhaps most importantly, most plants (perhaps not hemp!) are not limited by the photosynthesis they can perform even down to quite low light levels.
This link shows many real life action spectra, far far different from the graphs of chlorophyll absorption that plant light sellers like to show. Notice that in many cases, green light is comparable to blue, or even better, although red is almost always the most effective in terms of sheer efficiency of photosynthesis. However, as any pothead will tell you, growing only in red light is a disaster due to lack of other light-induced functions that cause weak plants and etiolation. http://agi32.com/blog/category/horticulture/
[quote="iann"]The lights you see on eBay are cheap for a variety of reasons. Partly they are sourced directly from the far East, partly they cut some corners on quality. Hard to say if it is worth it or not. Is it a waste of money if individual LEDs start fading out after a couple of thousand hours? Do you have any way to be sure you are getting the performance that is claimed? Or does it make no sense to buy top quality that will last for 10 years of continuous use if they are obsolete after 18 months? And is it a waste of money if they set fire to your house?[/quote]
??? Wow. Did you really say that? Based on what? Assumptions? I have difficulty agreeing with these comments and wonder how you came up with that. I specifically looked for the "brand name" of Mars Hydro, as recommended on this thread, and so what they are made in China? Are you saying they can't make a quality product in China? Have you bought one and found that the LEDs fail after a couple thousand hours of use, or they are obsolete after 18 months? The precise units I bought (on Ebay) come direct from the Mars Hydro warehouse and are advertised at " Lifespan: 50000-100000 hours". If they're going to "fade out" in a couple thousand hours, I'd sure like to know about it. Before I bought my "cheap" units on Ebay, I checked the Mars Hydro website, and then sought the product, which I only then co-incidentally found on Ebay at killer deal prices. I almost bought the exact same thing from Amazon, which was $20 more (roughly 33%), but happened to notice hits on my Google search from Ebay. I also looked at reviews from others on various websites who also bought the exact product I did - all my research did not scare me away, to the contrary. Also, I bought one first, to check it out, was more than satisfied with my perception that they at least appear to be well made, and then bought more. I have 2 currently set up (set up the 2nd yesterday), absolutely love them, and have more on the way as well. Since the shipping is free, it makes no difference if I buy one at a time or a 1/2 dozen at once.
I bought some rather expensive Gasteria armstrongii hybrid Variegated seeds from a very reputable source, and sitting under those lights on seedling heat mats, they have already germinated in 12 days time from sowing. Although I don't think the actual germination is a function of lighting, I'm sure the subsequent growth most certainly will be. Let me say, the sprouted seeds look big to me after only a day or two, and nice and green as well. Also, my Aloe plicatillis seedlings which are sitting under those lights as well appear to have much improved their growth rates and color, already discernible after what I would have to say is very brief exposure to the new lights. So, although I don't also have a control group of the same things now not growing in the new conditions, and can't therefor absolutely say the excellent results are because of the new lights, my feeling is that it's indeed the case, and I am thoroughly impressed and happy with the product and early results so far.
By the way, the units are quiet, they don't even get hot (at all!), and are set up on programmable digital timers all plugged into surge protectors. I don't see how they could possibly catch on fire. If there was an electrical short, the surge protectors would cut off power to them instantly.
On the other hand, maybe you are saying the product is counterfeit? Mine were shipped from the Mars Hydro warehouse which coincidentally turns out is less than an hour drive from me. Or, are you inferring that they are offering heavily discounted prices during the holiday season because these ones are of lesser quality than the same ones sold at twice the price elsewhere? Do they have 2 factories, one that builds their "regular" ones, and the others which they discount in price because they cut corners on quality? It appears you must know something, because your opening comment seems quite authoritative. So, what inside information exactly do you have?
What I think is that they are immensely popular, are selling like crazy, and have made at least this unit available, at least right now, at a super price, using Ebay as a market to move extra units. Looks to be working, because the one listing I used to buy mine currently indicates they've sold 1,260 units. Oh, and they have 8930 feedbacks, 99.9% positive (user name marshydro).
In any case, I feel quite comfortable having bought my Mars Hydro units shipped directly from the nearest Mars Hydro warehouse, and am not second-guessing why they were being offered at fantastic savings. Anyway, that's just my opinion, based on having researched the product, having actually bought some, actually using them (albeit for a short time), and being thrilled to be using top growing lighting technology at surprisingly affordable prices. I think it's very possible, and actually likely, that Mars Hydro is trying to generate cash flow by selling discounted units on Ebay, rather than your explanation that they must have cut corners on quality for this product thereby being dumped on Ebay. I think it's also quite possible, that like everything else technological like TVs and electronics, that products get actually better and less expensive in time, and regarding these lights, their time has apparently come.
All light outside the peaks at ~450nm and ~650nm (blue and red) is of little use to plants, photosynthetically speaking, and is therefore wasted energy.
This is a common myth, with the sellers of plant lights only too happy to let it run. All light in the visible spectrum, and a considerable amount outside it, is of use to plants. Chlorophyll itself absorbs most strongly at the wavelengths you mention, but also at other wavelengths. A single chloroplast absorbs green light quite inefficiently, but a leaf or cactus doesn't just contain one chloroplast, so a considerable amount of green light is also absorbed. "Chlorophyll" is actually multiple related pigments, with the two dominant forms absorbing light strongly over the whole of the ranges at 400-500nm and 600-700nm. In addition there are other pigments that absorb light at different wavelengths from chlorophyll and transfer it into the photosynthetic pathway. Not all of this energy goes into photosynthesis, but some to other synthesis or regulatory functions. The total conversion efficiency of whole leaves ranges from well over 90% at its peak in the red and blue, to around 20-60% at its lowest, depending on the particular plant. Perhaps most importantly, most plants (perhaps not hemp!) are not limited by the photosynthesis they can perform even down to quite low light levels.
This link shows many real life action spectra, far far different from the graphs of chlorophyll absorption that plant light sellers like to show. Notice that in many cases, green light is comparable to blue, or even better, although red is almost always the most effective in terms of sheer efficiency of photosynthesis. However, as any pothead will tell you, growing only in red light is a disaster due to lack of other light-induced functions that cause weak plants and etiolation. http://agi32.com/blog/category/horticulture/
While you are technically correct to disagree with the statement as said "All light outside the peaks...", to the larger extent, the light outside the peaks indicated are largely wasted, in terms of $ spent / energy used / useful spectrum produced relating to grow lights. Plants do have 3 receptors that respond to different parts of the spectrum; the phytochrome receptor responds to the red part of the spectrum, cryptochrome responds to green and blue light, and photropin responds to blue light and controls plant growth. However, to a great degree, plants we see as green in color are so because green light is largely reflected, and not very useful to the plant. As it turns out, the newest LED lights (red, blue) are apparently immensely effective, and due to capitalizing on the most useful ("most strongly" as you yourself put it) wavelengths and in using LED technology, energy used and $ spent can be focused on what are apparently the most useful light spectrum portions for growing. More importantly, from my point of view, is that very affordable lighting that uses these most important portions of the spectrum allows a hobbyist such as myself to grow outside of the traditional seasons, without traditionally associated prohibitive cost. Artificially, it can be virtually optimal growing time year round by augmenting with these lights, especially early and late in the day, when it's dark, and even compensating for cloudy, dark, gloomy winter skies. I'm no longer stuck waiting until spring comes to plant seeds and otherwise achieve effective growth off-season.
Interesting discussion we are having here regarding grow lights. So thankful to have stumbled upon this recently.
Spinesandrosettes, I dont believe Ian meant any harm with this
" The lights you see on eBay are cheap for a variety of reasons. Partly they are sourced directly from the far East, partly they cut some corners on quality. Hard to say if it is worth it or not....And is it a waste of money if they set fire to your house?"
Who wants their house to burn down, you know? Some of the lights on the market today that do come from China are a complete waste of money and are poorly built, feel free to look up reviews on various cannabis websites. Even Mars Hydro states that the replicas of their product that are defective and faulty. China also doesnt have the finest track record in various industries when it comes to quality control and consistency, one can go on and on for days about this.
The Mars Hydro ones had consistently good reviews from what I've come across thus far, which is why Im considering them myself. If you take a look at some of the 'grow logs' of people experimenting with different lights, several individuals go on to state that grow lights produced in the UK like Budmaster for example, are constructed with more finesse than those produced in China, with higher quality components internally, and yes this is reflected in the much higher cost as well.
Here are some articles I've bookmarked discussing the role of green in photosynthesis worth checking out: http://msue.anr.msu.edu/news/green_ligh ... ant_growth http://m.pcp.oxfordjournals.org/content ... 4.full.pdf
While plants require strong red and blue elements of the light spectrum, they do utilize green, violet, and yellow in smaller quantities. Im not a botanist, but I am curious to know the role of the other spectrum colors in the plants development.
I see. If there are various other lights other than Mars Hydro on Ebay, and of specifically poor quality, then that certainly would explain the comments as being more reasonable. I didn't look at all the alternatives, I specifically tuned my interest to the Mars Hydro, liked very much what I found, and then only coincidentally found them to be currently available on Ebay at amazing savings; in my case, direct from the company itself. I did briefly look at a couple of comparable offerings on Ebay in that same category, but nothing else really compared to the Mars Hydro in perceived quality, and in price, which is why I would not be aware of potential problems or fire hazards with other brands, because I did not bother reading reviews on the competitors, since I was already quite satisfied with MH. So, when I read that generalized comment about cheap lights on Ebay, I took that to include the "cheap" (in price) lights I bought on Ebay from Mars Hydro. Without researching the subject to death, it's my impression they are one of the leaders in the market and offer a great product, especially for the money.
Personally, I am blown away that I can afford and afford to run such an effective, simple (just hang it and plug it in) system, and respected name product for my purposes and that a whole new world of around the seasons growing has opened up to me.
By the way, there is zero chance my house (or greenhouse) will burn down due to these lights. They generate no heat to ignite anything combustible, and apart from that, that's what circuit breakers and surge protectors are for, to ensure against short circuits causing a fire.
Anyway, I appreciate your clarification on the comments I found as questionable.
Personally, I am sold on the technology as implemented and made available by Mars Hydro. At those prices, I'm going to have several more in use within the next month.
iann wrote:This is a common myth, with the sellers of plant lights only too happy to let it run. All light in the visible spectrum, and a considerable amount outside it, is of use to plants. Chlorophyll itself absorbs most strongly at the wavelengths you mention, but also at other wavelengths. A single chloroplast absorbs green light quite inefficiently, but a leaf or cactus doesn't just contain one chloroplast, so a considerable amount of green light is also absorbed. "Chlorophyll" is actually multiple related pigments, with the two dominant forms absorbing light strongly over the whole of the ranges at 400-500nm and 600-700nm. In addition there are other pigments that absorb light at different wavelengths from chlorophyll and transfer it into the photosynthetic pathway. Not all of this energy goes into photosynthesis, but some to other synthesis or regulatory functions. The total conversion efficiency of whole leaves ranges from well over 90% at its peak in the red and blue, to around 20-60% at its lowest, depending on the particular plant. Perhaps most importantly, most plants (perhaps not hemp!) are not limited by the photosynthesis they can perform even down to quite low light levels.
I don't really see that this counters his argument as I don't think he was saying they wouldn't absorb any light at this level, just that they're less efficient at it as you suggest, and as such it means there is more wasted light than if you simply stuck to the more efficient wavelengths. If you're losing between 40% and 80% of light energy outside of those wavelengths against only 10% in then it still makes far more sense to stick to those wavelengths because you're still just wasting energy otherwise.
Mintylemonade wrote:Who wants their house to burn down, you know? Some of the lights on the market today that do come from China are a complete waste of money and are poorly built, feel free to look up reviews on various cannabis websites. Even Mars Hydro states that the replicas of their product that are defective and faulty. China also doesnt have the finest track record in various industries when it comes to quality control and consistency, one can go on and on for days about this.
Frankly the same can be said of replicas and fakes from any country though. I have two different types of Mars units too and the idea that they're likely to burn your house down is laughable, frankly my old British built reflector with it's T8 bulb was always far far more of a fire hazard because the build quality was poorer, and the amount of heat it kicked out was ridiculous such that I had to keep it well away from anything to safely vent.
The problem is that dodgy electrics from anywhere can burn your house down, pretending that LED units from China are somehow more likely to do this is just simply fear mongering against what are frankly great, well built, and drastically more energy efficient products. Mars ships to EU customers from within the EU, and to be able to store their product in and sell to EU countries like the UK and Germany they have to adhere to the exact same electrical safety and other standards of consumer rights protection as any other product from the UK or EU. Due to the build quality and low heat output, the Mars LED units are I suspect one of the single safest methods on the market of providing artificial light to your plants. They're certainly far safer than any fluorescent or halogen option, whilst also being cheaper, have a longer lifespan, and are more efficient too. What's not to like?
Having just set mine up, it's amazing how toasty it gets in these things! I've added a heat mat so as to aim for a substrate temp in the 80-90's. I think I'll introduce my plants gradually as it's pretty intense compared to recent summer growing conditions.
What are people doing about ventilation in their tents?
Deltron wrote: ↑Sat Sep 01, 2018 2:07 pmWhat are people doing about ventilation in their tents?
I am in the process of building a fixture that would cool the plants with outside air during winter freezing temperatures. It may sound crazy to use air at -20C to cool down desert plants, but it is not. My trial last winter showed that I needed two 4" fans (one inlet and one outlet) spinning at crazy rpms (the noise can be easily heard in another room) to keep an 8 sqft box at +15C. And this is without any lights on! Air at -20C mixes with warm air pretty much instantaneously once it enters the grow box, so I don't think the plants would get frost bites. Let me know if anyone is also contemplating a similar set up. I am planning to use it for winder growing mesembs.
