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Lumens Per Watt

Discussion in 'CFL / Fluorescent Lighting' started by kennewickrockerguy, Mar 5, 2010.


    kennewickrockerguy Active Member

    I have looked on a few sites and browsed the forum and was hoping someone could give me some experienced info on what 6500K and 2700K give the most lumens per watt. Hopefully someone, somewhere has compiled all this data.

    stumps Well-Known Member

    not sure what you want to know?

    stumps Well-Known Member

    Just wondering. Are you related to the kennewick man? :) The Kennewick man was hanging out near my old fishing hole. Then they took him away.

    supertiger Well-Known Member

    higher wattage HPS lighting will give you the most lumens per watt, followed by an eight bulb 48" T5 HO, followed by Metal Halide, followed by CFLs.( higher wattage CFLs give you less lumens per watt then the smaller ones)

    To make a comparison we will look at 400 watts of power.

    400 watt HPS
    55,000 lumens or 137 lumens per watt

    432 watt, 4' 8 bulb T5 HO
    40,000 lumens or 92.59 lumens per watt

    400 watt MH
    35,000 lumens or 87.50 lumens per watt

    420 watts of CFL
    I'm not sure but I don't think it's any better then the above 87.50 lumens per watt. I've never took the time to add up 400 watts worth of 42w CFLs in lumens.. I believe a 42w CFL get's 2800 lumens? So I guess 10 of those ( 420w @ 28,000 lumens ) would certainly be worse. CFLs really are the bottom of the barrel as far as efficiency when disregarding incandescents. The advantage to CFL use is easy placement around and in your canopy. I think CFLs are good for supplimental lighting and rather poor as a main source. This is not to say you can't grow something with CFLs because we all know it works but the results will never be the same as an eight bulb T5 HO for veg and an HPS for flower because the efficiency is very poor. You would need 600+ watts of CFLs to match the 432 watts of T5 HO light.
    kennewickrockerguy likes this.

    stumps Well-Known Member

    I use 2 100w cfl's. for veg. would much rather have the mh going.
    full of purple likes this.
    Shrubs First

    Shrubs First Well-Known Member

    The bulbs in your kelvin ranges will produce similar lumens per watt... so like a
    6500K bulb will produce the same lumens as other 6500K bulbs because the
    lumenosity function is determined by wavelength. Meaning 6500K bulbs will put
    out the same wavelengths, and assuming they are the same amount of power as
    eachother each bulb will produce the same lumens. The reason HPS bulbs have more
    lumens per watt isn't because they put out more light, it is because the human
    eye perceives it as brighter because the human eye detects different spectrum
    lights differently. As of yet, I have no reason to even use HPS bulbs, I don't think
    I ever will, in my opinion it is a deficient light and not suitable for a plant to fully metabolize.
    mauricem00 likes this.

    JN811 Well-Known Member

    I believe that they give off the same amount of lumens just in different color spectrums.. heres some good info if u havent read it..

    Things to know about lighting
    Things to know about lighting
    Color rating- Measured in Kelvin (K). The higher the number, the more bluish the light. 4000K-7000K is mostly on the blue side of the spectrum, while 3000K and under goes from a white spectrum, to a redder spectrum.

    How much light is needed?
    The minimum amount of light required by marijuana plants is around 3000 lumens per square foot. However, it's not 100% accurate, since although you may have a 10,000 lumen light, the amount of light that reaches the plant varies with the distance between the light and plants, and reflectivity of the grow box. The ideal amount is somewhere around 7000-10,000 lumens/sqft, and as long as the plants do not burn, as much light can be used as you want.
    (*note, the sun produces about 10,000 lumens/sqft, on a sunny summer day).

    Determining lumens for your grow area:
    Determine the square footage of your area (example in a 4 foot by 4 foot area, there is 16 square feet)
    If you have a 1000 watt High Pressure Sodium, that produces (approx.) 107,000 lumens.
    Divide this by 16 (your square footage) 107,000 / 16 = 6687 lumens per square foot.
    So just divide the total amount of Lumens, by the total amount of Sq ft, and thats your lumens per square foot.

    How far away from my plants do the lights go?
    The lights in your grow room should be as close as possible to the plants without burning them. There is no such thing as too much, unless there is sufficient heat to dry out and burn the leaves. A good rule is to put your hand under the light, if its too hot for your hand, chances are that the plants will be too, so move the light up until your hand feels more comfortable. For seedlings and clones, I keep them a little further away from the light, because they are very susceptible to burning and drying out, at these stages.

    Efficiency is very important when choosing a type of light. The wattage is not the most important thing, as you can see below, different types of light produce different amounts of lumens per watt. A 300 watt incandescent will produce about 5100 lumens. While a 300 watt Metal Halide (just an example, they do not come in 300 watts), will produce 27,000 lumens. Obviously far more efficient for growing, while still using the same amount of electricity.

    Approximate light production:
    Incandescents: 17 lumens/watt
    Mercury vapor: 45-50 lumens/watt
    Fluorescents: 60-70 lumens/watt
    Metal halide: 90 lumens/watt
    High pressure sodium: 107 lumens/watt

    Incandescent lights: Incandescents are the most popular type of lights in the world. They may come advertised as incandescent, tungsten, quartz, halogen, or simply standard. The important thing about incandescents is this: they suck.
    There are some incandescents which are sold as 'grow lights.' They usually have a blue coating and usually come in 60W and 120W sizes. While they may seem like a good choice to new growers, they are next to useless; they produce some light at a usable spectrum, but only have about a 5% efficiency and generate more heat than usable light. Most of us have these in our homes right now. Don't use them for growing, instead opt for a Compact Fluorescent as a cheaper but more efficient alternative.

    Fluorescent lights: Fluorescents are a lot more useful than incandescents. Their efficient enough, and cheaper than HID lights. Compact fluorescent tubes are popular with growers because of their good output to size ratio. Compared to standard 4' tubes, compact fluorescent bulbs are smaller, and more can fit into a given area. Fluorescents are good for small grows on a tight budget, and for novice growers, since they do not require any special sort of wiring or understanding of the necessary bulbs for a given fixture, and are very widely available.
    Fluorescent lights come in many different Kelvin ratings; often the spectrums are labeled on packaging as being 'cool white' or 'warm white.' Cool white is more blue, and is good for the vegetative stages of growth, and warm white light is more orange or reddish, and is best for the flowering stage.

    High Intensity Discharge (HID) Lighting Systems:

    Mercury Vapor (MV)
    Mercury vapor lights are not the most efficient light for growing. They are very bright, and relatively cheap. They do emit light at the wavelengths necessary to support your plants growth, but not nearly as good as a MH or Hps light. Much of the light emitted by MV lights is bluish-white. Street lighting is what most MV lighting is used for.

    Metal Halide (MH)
    Metal halide lighting systems are optimal for use in the vegetative phase of growing. They emit mostly blue light, which encourages vigorous growth of foliage. They are very efficient, but can get rather expensive to start with; fluorescents may seem more appealing because of their lower price, and they are not much different when compared on a lumen-to-lumen cost level. These lights can be used through-out the grow, but will most likely result in light, fluffy buds.

    High Pressure Sodium (HPS)
    High pressure sodium lights emit mostly orange, yellow, and red spectrum light, which is perfect for the flowering stage of the plants growth. They are (in my opinion) the most efficient type of light available for any application. HPS lights can be used through-out the entire grow. They produce more dense and usually larger buds than any other light.
    HPS lights are generally a little more expensive than MH systems of similar wattage. They are more commonly used by experienced growers because of their ability to produce tighter buds, higher lumen-output-per-watt, and will produce from start to finish.

    I'll also add this graph below, i hope this post helps some of you out.

    JN811 Well-Known Member

    you are right about the majority of that, but my plant grow GREAT under a HPS so you shouldnt knock something before you try it..furthermore I have NEVER seen any cfl or led or t5 grows that can compete for the same amount of $ spent..

    stumps Well-Known Member

    Hey Shrubs I don't get what your saying. hps has more power then a cfl. so more light gets to or into the plant. I've never flowered with cfl. But I veg with both cfl and mh. I do use cfl for side light.
    Shrubs First

    Shrubs First Well-Known Member

    I've seen some good grows under HPS.. But do I think those plants got to their
    full potential? Quite honestly no, I just don't like the light spectrum, it peaks at
    560 nanometers. That is the reason why HPS have so many Lumens per watt.
    Matter of fact I shouldn't even be in this thread anymore, I don't measure my
    bulbs in Lumens. PAR watts per square meter, PPF PAR and YPF PAR are all
    legitimate, ways of measuring the light output of lamps for plant growth. They
    do not involve the human eye response curve which is irrelevant for plants.
    *Cough Cough* Lumens

    I use Sunpulse Bulbs, Pulse Start Metal Halides.... I like them much better than
    HPS and standard Probe Start Metal Halides.... They perform for me very nicely.

    Clearly. My whole statement was based on the assumption that the two bulbs
    were of equal power.

    mauricem00 and coolj like this.

    fredsgrow Active Member

    23 watt CFLs tend to be the most efficient "economy bulbs." Most will put out roughly 1600 lumens (69 lumens/watt) whereas 42w lamps put out 2600 or so (61 lumens/watt). I think I'll have a pretty healthy grow with 6-8 CFLs in a 3.4 sq ft area with 1-2 plants. If you're going much larger than that you'll want HID lighting, CFLs are really only good for small numbers of plants you want to keep small for whatever reason;)

    kennewickrockerguy Active Member

    I plan on 8 - 85 watt 6500K for veg 4200 lumens each in a 2 x 5 x 7ft tall room. I hope thats a good start.

    stumps Well-Known Member

    8x85w is going to put off some heat. you'll need good venting for the heat. At 45.00 a pop on lights you would be money ahead to get a 400w hid. lol with that said you would be good with the cfl's in your room size. before you buy lights you need to come check out my little grow.

    supertiger Well-Known Member

    It's also an overly expensive and an inefficient way to setup a grow room of that size. Get a 48" T5 HO, 8 bulb light fixture. It's under $220 including bulbs and will outperform your 680 watts in lumens and the heat will be 80% less. So why would you buy those CFLs? Honest question, why do people invest so much money in hot CFLs beyond a PC style grow when T5 HO are so much better? Your 4200 Lumens x 8 lights = 33,600 lumens. And your using how much watts? 680? And what cost for plugs and fixtures? The 8 bulb T5 HO consumes 432 watts and puts out 40,000 lumens @ $220.

    CFLs should stick to PC grows or anything around 2' x 2' or less. Go get a T5 HO fixture. Spend your saved money on great ventilation.
    mauricem00 likes this.

    stumps Well-Known Member

    I've never really looked into
    T5's. guess I should. Yes the 2x was messing me up. the tubes would be a good idea for that space.

    bubblegoogles Member

    Small CFL's are less efficient than large ones. The best a spiral cfl can do is 61-63 lumins/watt the U type cfl ( 105 watts and upto 300 watt) are at 65 lumins/watt there is a new player in cfl's called the rosebud which puts out 75 lumins watt simply by the shape of the tubes allow more light to come out of the inner tubes it also runs cooler because of larger air gaps. check out pics. These are cheap too! they are $35 ea. at enviro-techlighting.com.

    Attached Files:


    supertiger Well-Known Member

    That still doesn't beat the 92.59 lumens per watt you get with HO T5's.. Not to mention the significantly reduced heat. Like up to 90% less heat.. CFLs cost more and provide less.

    stumps Well-Known Member

    Can you get 54w tubes that are higher or lower then 5000k??

    bubblegoogles Member

    Actually it's cheaper to go with the cfl's still. T5 at 432 watts is $220 the rosebuds are $35 ea and are 105 watts ea and use a standard lamp base. 4 rosebuds are $140 and give you 32000 lumins@ 420 watts. The heat is not as warm as the normal spiral cfls they feel about the same heat as T5's.

    supertiger Well-Known Member

    And is that a complete setup or do you still need 2 110v to E27 lamp plugs and 2 Y's? Does that include a reflector? To reach 40,000 lumens you would need 5 bulbs, plus 5 reflectors, plus the adapter plugs etc.. Performance can't be compared unless as I said before, your using a very small grow area. (Like 2' x 2' or less)

    The reason performance can't be compared is because although your small little CFL may put out 8,000 lumens, it's only doing so from a very small source point, which means light intensity will drop off and the CFL will cover a much smaller area compared to the 4' T5 which is throwing 5,000 lumens accross 4 feet.

    Best advice is to get a light meter which 99% of CFL growers fail to do. If you looked at a side by side comparison of a 4' 8 bulb T5 HO lamp and 5 of those rosebud CFL's in a 2' x 4' area, you would find the light meter shows multiple pockets of significantly reduced light compared to the 4' T5's.

    I hope that makes sense.

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