We have a debate!!! Need everyone's imput!!!

bump 4 votes

bump 4 votes please?

I just dont feel Lumens are an accurate way of measuring the amount of light that your plant is using and how effective it is

What is Lumen output of these lamps ?
Though given, it is irrelevent ! Lumens are for Humans not plants ! Lumens measure how we see light. Our eyes prefer green light. Green light has the most Lumens, Red and Blue the least. Most fluorescent lamps are made to look bright for humans by adding huge spikes of greeny yellow light.
Lumens only measure how BRIGHT the light appears to us.
Lumens cannot measure light useful to plants

^just saw this in another thread.

I belive that the first agument is correct! The more cfls you have the more covrage you get on your plant. that is why they spread the lights around the plant. You only get so many lumens out of a cfl and it dimineses the farther it travels from the bulb, so you add lights to get the coverage you need to saturate the plant with light. So the more lights you add the more Lumens you get at the places the plant needs them.peace man

In boating terms if you have a boat with a 40hp motor and add another 40hp motor you don't go twice as fast you can haul a heavyer load and can get it up to speed faster.In other terms you can add more plants, or grow them bigger with more hp or bulbs. peace man

interesting i see what the light meter says but to say that 2 cfls next to eachother is no better than 1 cfls goes against all i understand if you had 1 plant under 1 42 cfl and 1 plant under 2 42 cfls even with the bulbs next to eachother the plant with 84 w is going to grow better that is not debateable. ive tested this.

I'd have to believe that post with the lux meter reading....it seems to say it all. The reason more cfls are better is because 1 will only shine on part of a plant. However, check out this link...scroll down to just below where it says "About This System" Its a 2 bulb t5 unit. It says each bulb puts out 5,000 lumens and after it says This system emits an incredible 10,000 lumens!
So what the crap are we suposed to think now?
Compact T5 FLUORESCENT GROW LIGHT Fluorex 2 TEK 400 hps - eBay (item 180224080362 end time Apr-06-08 12:00:00 PDT)

can anyone give an honest to god answer...my thinking is that if all the people on this website cant answer the question, then there might not be a viable answer to it. it might just be one of those things we dont know yet. cause i sure as hell have no idea after reading all this and im a pretty smart fella. haha

meter or not to say the plant is not effected by 2 bulbs of equal intensity as opposed to 1 does not correlate with reality in this physical world. i am trying to please cannabis plants not photo-receptors the lumen output that the device reads does not correlate to the plants usage of available light energy. live organisms are indescriminate in there atempt at growth and life.

alright did some scavaging through my optical physics books and here is what i found.
alright im a mechanical engineer, so dont hate me for having optics books laying around. haha. in my optical physics class i took last spring we learned about light dispersion. light dispersion, simply put, is when light waves coincide with each other and instead of changing the amplitude of the wave, it changes the frequency (or the lumens). it can also change the color of the light when passing through a solid medium...think of a rainbow. what does this mean though? through basic physics we can find that the interfering frequencies can cancel each other out. so when loudblunts took a reading with his meter, the lumens could be cancelling each other out. but when shenagen added that post it confused everyone. one way the compay could achieve the addition of lumens is by adding a phase shift to the light waves...or moving one light back or foward so the waves would coincide and not interfere. so in opitcal theory...they are both theoretically possible...the phase shift just extremely hard because the bulbs would have to be positioned by a laser into a ballast which was machined out of a laser cnc machine. not alot of people have those things laying around. not for sure if this helps but figured id throw it out there and see if it does.

well if its true that the more CFL lights you add the lumes doesn't go up but I think that if its realy true then the more CFls you run (ie. 900 lunes) then the plant should have more lume resorces to use but then wouldn't that increase the Lumes that it can use?

What I belive is that the more lights you add then the more the resorces the plant has to use. If a grower used 5 HPS bulbs for 1 plant it should grow faster. I added lights for my girls and in 1 month they doubled in size, so if addling more lights doesn't do any thing then why did my girls grow fast? they are getting close to the same hight as their mom plant in less time

Rope Smoker said:

In boating terms if you have a boat with a 40hp motor and add another 40hp motor you don't go twice as fast you can haul a heavyer load and can get it up to speed faster.In other terms you can add more plants, or grow them bigger with more hp or bulbs. peace man

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I think this is one of the better analogies. You can add lumens with more bulbs, but you can't add intensity. Lumens is just a measure of brightness to the human eye. I think that what is more of a concern is not Lumens but PAR and Usable Spectrum for plants.

I remember a study being done that had two lights of equivalent wattage, but the perceived brightness or lumens varied because the human eye is more sensitive to some colors than to others.

Illuminance - Wikipedia, the free encyclopedia
Irradiance - Wikipedia, the free encyclopedia
Radiometry - Wikipedia, the free encyclopedia

The lumen is the photometric unit of light output. Although most consumers still think of light in terms of power consumed by the bulb, in the U.S. it has been a trade requirement for several decades that light bulb packaging give the output in lumens. The package of a 60 watt incandescent bulb indicates that it provides about 900 lumens, as does the package of the 15 watt compact fluorescent.


The lumen is defined as amount of light given into one steradian by a point source of one candela strength; while the candela, a base SI unit, is defined as the luminous intensity of a source of monochromatic radiation, of frequency 540 terahertz, and a radiant intensity of 1/683 watts per steradian. (540 THz corresponds to about 555 nanometres, the wavelength, in the green, to which the human eye is most sensitive. The number 1/683 was chosen to make the candela about equal to the standard candle, the unit which it superseded).


Combining these definitions, we see that 1/683 watt of 555 nanometre green light provides one lumen. [Thus, the lumen scale is calibrated to a point in the spectrum that photosynthesis doesn't use -- Mac]


The relation between watts and lumens is not just a simple scaling factor. We know this already, because the 60 watt incandescent bulb and the 15 watt compact fluorescent can both provide 900 lumens.


The definition tells us that 1 watt of pure green 555 nm light is "worth" 683 lumens. It does not say anything about other wavelengths. Because lumens are photometric units, their relationship to watts depends on the wavelength according to how visible the wavelength is. Infrared and ultraviolet radiation, for example, are invisible and do not count. One watt of infrared radiation (which is where most of the radiation from an incandescent bulb falls) is worth zero lumens. Within the visible spectrum, wavelengths of light are weighted according to a function called the "photopic spectral luminous efficiency." According to this function, 700 nm red light is only about 4% as efficient as 555 nm green light. Thus, one watt of 700 nm red light is "worth" only 27 lumens. [This suggests to me that lumen ratings would be misleading for comparing, say, HPS to CMH. CMH is much greener light, and will appear to be 'worth' more lumens, even though it should be less useful to flowering Cannabis.-Mac]

Because of the summation over the visual portion of the EM spectrum that is part of this weighting, the unit of "lumen" is color-blind: there is no way to tell what color a lumen will appear. This is equivalent to evaluating groceries by number of bags: there is no information about the specific content, just a number that refers to the total weighted quantity.

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does anyone actually think adding energy through more cfl bulbs or any other energy source even if at equal distance is ineffective because of readings of lumen output registered by a device that is subjective. yes lumen output read by the device will appear the same but there is 2 times as much energy available to the plant. penetration is very important with cfls but double the light is double the light to say this does not promote biological activity in plants is a big statement. the meter will read the same intensity but there still is twice the amount of actual energy involved i am confused as to what people are triying to explain or argue

bicycle racer said:

i am confused as to what people are triying to explain or argue

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That's OK--so are they. Yes, more lights means more light. But not necessarily any more intense light. The growth of Cannabis is affected by both the amount of PAR energy available, and it's intensity. Conventional wisdom says the amount of light is important to general plant growth and vigor and its intensity to flowering yield/potency, but I'd imagine that such a rule of thumb is far too generalized.

Maccabee said:

That's OK--so are they. Yes, more lights means more light. But not necessarily any more intense light. The growth of Cannabis is affected by both the amount of PAR energy available, and it's intensity. Conventional wisdom says the amount of light is important to general plant growth and vigor and its intensity to flowering yield/potency, but I'd imagine that such a rule of thumb is far too generalized.

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I absolutely agree with this statement. No one on this entire board has stated just what the minimum intensity or max intensity is. Apparently because people do get buds (albeit less dense than hps but no lack in potency) the CFL intensity seems at least adequate.

but when shenagen added that post it confused everyone. [/quote]


Hey...I was allready confused too! Its funny, when I first read the posts I was under the impression that you can't add lumens...but then I remembered my light I had bought and its claims(the link provided earlier) Your explanation seems sound...but I'm no mech. eng... wanted to be when I was young though.

The whole putting more cfls thing works because as I said before, one cfl only reaches part of the plant. So to reach the entire plant with light you have to get multiple bulbs.

Maccabee said:

That's OK--so are they. Yes, more lights means more light. But not necessarily any more intense light. The growth of Cannabis is affected by both the amount of PAR energy available, and it's intensity. Conventional wisdom says the amount of light is important to general plant growth and vigor and its intensity to flowering yield/potency, but I'd imagine that such a rule of thumb is far too generalized.

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Really I think you nailed it. Adding more CFLs will increase coverage. But they do not add up to be a more intense, penetrating light. I witness this with entertainment fixtures all the time. Say five 1000w lights in the same focus will give more coverage but are not as intense as one 5000w lamp. Often times I am more concerned about Color Temperature but intensity makes a huge affect on this as well when dealing with incandescent fixtures. There is a huge difference just in bulb types as far is what is considered "usable" light and lumen output per watt.

I would never argue that more Fluorescent fixtures will not equal better growth and produce improved results over just one lamp. But, plants in vegetative states do not need as much light penetration as they do during flower. Smaller plants may do very well with fluros during flower, but will not reach max yield. Ive experimented several times and this is just simply true. The same amount of watts in fluro will NOT equal the same results as a single HID lamp.

Honestly I think many companies are actually giving more of a radiance reading for the lumen output of their fixtures. (radiance is brightness at the point source). fluro loses its luminosity very quickly as you get farther from the point source.
-The readings for lumens should be taken approx 1' from point source but I am skeptical.

In my mind it is misleading to tell a newb grower that if they just add a bunch more fluro they will get good results. Although some folks do fine this way their money would be better spent buying the same wattage HID as they would have planned to cfl and the results would be better. I guess if your growing one plant then what the hell... but still there are way cheap 60w hps out there... People bring up heat all the time with HID, but the fact is that 1 watt of energy produces the same amount of heat, regardless.

put simply 10 cfls of equal wattage will produce more cannabis than 5 cfls of same wattage its funny what people will argue about