Lumens Vs Spectrum

Discussion in 'Advanced Marijuana Cultivation' started by RickWhite, Jan 30, 2010.


    RickWhite Well-Known Member

    Is there and reliable data on what is more beneficial to a plant?

    It seems that my 250W Hortilux Blue MH with a 6500K temp is outperforming my 600W Hortilux HPS for vegitative growth.

    It's hard to tell but I'm wondering if going with the 1000W 6500K MH for the entire grow isn't the way to go. Or maybe, the new ceramic MH bulbs.

    FuZZyBUDz Well-Known Member

    well a 1000 watt HPS kiks out like 140000 lummens but a a MH kiks out 100000, but with the HPS u will deffinately have sum dence buds, MH have a risk of a more airy buds with the less lummens, but u really got more potency out of the MH compared to the HPS.

    satica Well-Known Member

    I begin with metal halide 600 watt for veg that keep the plants shorter and thicker.when Flowering comes I just switch to one day metal halide and one day 1000 watt HPS .

    overally, IMO it is the best way to use good thoings of MH and HPS. I think MH has been under rated .Its a good source of light especially for veg.

    In your case if it is outperforming your 600 watt hps then maybe something is wrong with your hps ballast or bulb since the difference is not that much .


    T.H.Cammo Well-Known Member

    [​IMG] Lumens Vs Spectrum

    I'm not sure, exactly, what you're asking! But how's this?

    A whole bunch of lumens won't do a damn bit of good, if they're the wrong spectrum. But even a single, little 25 watt, "Daylight" CFL will Veg something - impressively well!

    "Spectrum" is of paramount importance, "lumens" is a slippery slope!

    RickWhite Well-Known Member

    I have used the enhanced blue HPS bulbs for some time and have hed decent results. But, other than conventional wisdom, I have yet to see anything concrete that demonstrates any benefit from a HPS vs a MH. In fact, I am beginning to wonder if running exclusivly MH isn't the better way to go. After all, people get great results from MH as well.

    plaguedog Active Member

    Does anyone have any experience with the Ceramic Metal Halide bulbs? They put out less lumen per watt but supposedly the spectrum has much more blue then the standard HPS and much more red then the standard MH. I think 250 watt and up they can only be used in a standard magnetic ballast, not digital. I'm really thinking about getting one for my small 250 hps grow.

    here is another site with decent info on them:

    Here are some other newer technology lights also known as CDM from phillips. Supposedly the 210 watt light is comparable to a 400 watt MH with a fuller spectrum.

    RickWhite Well-Known Member

    I am also very interested in these bulbs. They come in up to 400W and use a standard HPS ballast. Not digital and not switchable.

    But yes, they are an almost perfect spectrum. Hortilux however, makes a 1000W blue bulb with agreat spectrum though not as much reds as the CMH. But, from what I have been noticing, it looks like the plant uses the red spectrum to grow stem and the blue to grow foliage. I want foliage, not stem.


    On another note, has anyone ever seen proof that higher reds promote better flowering? What I've heard is that some believe that the harvest sun includes more red light so it must stand to reason that more red promotes flowering. I'm not convinced this is true. If anyone has proof, I'd love to see it.

    lmn8r Well-Known Member

    Plants are designed to grow in the SUN... Any artificial light that comes closer to that will give better results.

    High pressure sodium works because of it's raw power and efficiency. It concentrates nearly all it's energy as light into that ugly orange color peak around 589nm wavelength. Plants only absorb that type of light moderately, because it's not in the "butter zone" of photosynthesis. It is however, fairly close which is why it's used for flowering, and like I mentioned, it's raw power makes up it's lack of absorption.

    CMH lamps such as the Philips MasterColor series give off a little bit more red then the Hortilux Blue. In my opinion, CMH bulbs have the highest percentage of light absorbed by the plants when compared to all other grow light technologies. They are less efficient then HPS, more of their light is useful light within the 400-450nm blue and 600-700nm red range.

    It's mathematically calculable how much useful energy to a plant each type of lighting technology gives out. I did the calculations;

    I compared an EYE Hortilux Super HPS 400w bulb to a Philips MasterColor 400w CMH. The HPS bulb gives 55,000 initial lumens for 137 lumens/watt and the CMH bulb gives 34,800 initial lumens for 87 lumens/watt.

    Assuming all the factory specs, and rounding lumens down, I calculated the relative energies at 10 nanometer wavelength intervals from 400nm-700nm within the visible light spectrum; A total of 31 different measurements. I then compared Clorophyll A and B photosynthesis at each wavelength interval, and ran the numbers.

    In the end it turned out the HPS bulb had 12,318 lumens worth of useful photosynthetic penetration. This beat the CMH bulb with 9,903 lumens worth of useful photosynthetic penetration; The HPS beating the CMH bulb by roughly 124% overall. Predictably though, the CMH had a higher percentage of it's light used for photosynthesis, 28% of it's light used versus only 22% from the HPS.

    Looking at a narrower scope, just veg/flower colors, the HPS is 141% better at flowering then the CMH, producing 4935 useful lumens within the 600-700nm "butter zone" compared to the CMH's 3478 lumens. The CMH had the HPS beat though for vegetative stage, 850% better at the 400-450 blue spectrum. The HPS only mustered 416 useful blue spectrum lumens, compared to the CMH 3514 lumens. Keep in mind though, this is a horticultural bulb with an enhanced spectrum, standard security light HPS would lose hands down to CMH.

    The conclusion? It's still not clear. If you had to use a single bulb throughout the whole grow, the CMH may have the advantage because it handles the veg. stage so much better, while only trailing HPS during flowering. On the other hand, if you have the option of swapping out bulbs, you'll want to use the CMH for veg. and HPS for flowering. If your looking for the best possible light conditions, I would suggest one of each. What's interesting is the normal metal halides can easily push 110 lumens/watt. If they are to improve CMH technology in the future to make it more efficient while keeping the same spectrum, at that level it will beat out the HPS in all circumstances.

    My personal opinion about CMH bulbs; I think they're the best artificial light source for growing yet, beating out HPS. The balanced spectrum plus UV light emitted from CMH bulbs has additional, unmeasured benefit for flowering cannabis. I'm convinced, but until someone compares the two in laboratory conditions a lot of people won't be. Your welcome to make your own conclusions.

    If anyone wants to see my spreadsheet with all the numbers let me know i'll post it.
    Uncle Ben

    Uncle Ben Well-Known Member

    There isn't, I've done the experiment using a regular HPS from start to finish. There was none of the favorite forum paradigms - excessive stretching, lack of potency, poor plant health, etc. Both lamps are full spectrum, it's just that when folks look at the spectral output graphs, they think the plant needs more of this and that. Spectral output is overdone, just like nutes, additives, and all the other stuff folks tend to throw at their plants.

    Vendors are the ones that really play the spectrum thing up, as they should - they're in it for the money. Conversion lamps, hoods, enhanced this and's all about the money. Plant doesn't care, only its owner cares.

    RickWhite Well-Known Member

    I'd love to see it. In fact, can you upload the file? Also, I'd like to see the literature you are using to determine what wavelengths are the most effective for vedge and flower. Do you know anything about what wavelength produces stem elongation?
    Uncle Ben

    Uncle Ben Well-Known Member

    Thanks. I too have graphs since I studied this stuff to death. Here's an example of one lamp plants.

    Attached Files:


    RickWhite Well-Known Member

    So UB, you are saying that sheer light output trumps color?

    have you also tried an all MH grow?

    RickWhite Well-Known Member

    OK, I did some reading and it appears that the important wavelengths for plants are 425nm - 475nm & 650nm - 700nm.

    The CMH bulb in a 4000K color produces around 15 times more relative energy in the blue range and 3-4 times as much relative energy in the reds than does a bulb such as the Sun Agro HPS. I forget what the overall difference in Lumens is but it is nowhere near these numbers.

    Unless I am dramatically misunderstanding something, the CMH should be far more effective.

    figtree Active Member

    Yeah rick, blue spectrum is better for veg, but if you can have both your even better. i actually use 6500 for veg and 2500 for bloom. i wish i could use both for both all the time. each spectrum will benefit in a different way, is good for leaves and foliage, and red is good for roots and flowers.
    This is a good question for the LED bunch, less lumens but right where you want with the spectrums.

    jawbrodt Well-Known Member

    I just wanted to add that the OP could be mistaken about the 250 MH beating the 600 HPS. It's a common for new growers to mistake stretching for vigorous growth, as I've done this myself, in the very beginning.LOL

    RickWhite Well-Known Member

    No, I'm no noobie. Forget the watts - the Lumens are the same the way I have them arranged.

    The key is that the MH is a 6500K bulb. The difference seems fairly clear - way more bushy and the leaves really reach for the bulb where as with the HPS they just kind of hang there.

    I might just bud one on it's own under the MH to see how it compares.

    lmn8r Well-Known Member

    My apologies if I made any math mistakes, it was late and I had been programming all night. Your right about the percentages, I was thinking like a computer, where 100% == 0. The two main measurements are the relative energies and Chlorophyll absorption percentages, which are taken from another study probably unrelated to cannabis. Without knowing the nuances of the cannabis plant, all I can offer is each bulb's useful spectra for photosynthesis.

    One thing you should forget is the whole "6500k" kelvin color temperature system. This is a system that shows how humans perceive light, not how plants do.

    jawbrodt Well-Known Member

    Ahhh, okay. Sorry about that. :)

    Mcgician Well-Known Member

    I'm conducting a test trial right now, but it's between a standard EYE Hortilux Super HPS 1000W bulb vs one of the new Sun Pulse 1000W in the 3K spectrum. This is a halide bulb in case you weren't aware. In 4 weeks I should have some more definitive answers.

    plaguedog Active Member

    Well one thing is the CMH bulbs are about the same price point or lower then the expensive hortilux bulbs I believe. And if you want to cut down on heat a little bit they run somewhat cooler. The CMH also has a more comparable output curve as an hps, it lasts longer then a standard MH. I don't have one but I think I will purchase one and just see for myself when my hps bulb takes a dump.

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