# Do lumens really matter? Do they add up? Lighting experts apply within



## doobnVA (Aug 1, 2009)

Good morning 

So, this whole thing about lumens really confuses the crap out of me and I'm hoping someone can either explain or point me to some reading material that breaks it down in terms I can understand. Keep in mind that it's been more than 10 years since I've set foot in a math or science class 

Now, as I understand it, lumens don't really mean anything when it comes to how plants use light. Lumens are a measurement of light that's visible to humans, right? And somehow you have to convert that to something called PAR (what the crap does that stand for?), which is like, the amount of light available to aid in photosynthesis??? Basically, PAR is how much light the plants can "see" and use, right? 

But I'm assuming that generally, more lumens = more usable light?

I've also heard that lumens don't add up?

So if you're using 26W CFL @ 1750 lumens it doesn't matter how many you use, you're still only getting 1750 lumens?

It makes sense to me that a bulb I'm using on one plant at the end of the row isn't going to benefit a plant at the other end of the row...but the T5 floro 52Wx4 fixtures I see are advertised as putting out 20,000 lumens (each bulb @ 5,000 lumens).

I'm so confused.

Anyone want to shed some wisdom on this subject for me?


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## sogalax (Aug 1, 2009)

i have heard that lumens dont add up in terms of a bunch of cfls or even LEDS. wile this makes sense i also have a little voice in the back of my head that says two bulbs is twice they amount of light.

soooo i cant help but ill give ya a bump cuz i wana know too!!


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## smppro (Aug 1, 2009)

They add regardless of what people say, a handful of cfls will have more lumens concentrated in one spot than just 1 cfl alone


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## doobnVA (Aug 1, 2009)

Thanks, I guess it's the weekend and nobody wants to think too hard.

The voice in the back of my head tells me the same thing, and I've seen some CFL grows using lots of low watt bulbs to surround the plant with light and they seem to be pretty successful.

Hopefully someone will come along soon and make sense of this.


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## SHAWTYBANGBANG (Aug 1, 2009)

Plants "see" light differently than human beings do. As a result, lumens, lux or footcandles should not be used to measure light for plant growth since they are measures used for human visibility. More correct measures for plants are PAR watts, PPF PAR and YPF PAR, although each in itself does not tell the whole story. In addition to quantity of light, considerations of quality are important, since plants use energy in different parts of the spectrum for critical processes. http://www.sunmastergrowlamps.com/SunmLightandPlants.html


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## TLeom (Aug 1, 2009)

I think you are swapping lumens for kelvins. You cna add up the lumens but not the kelvins


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## BigBudBalls (Aug 1, 2009)

They do and they don't

Light diminishes further it travels.

Adding lights only gives you full power further away.

If I light one candle I get 400F If I light 10 I don't get 4000F.
(the heat from the candle *IS* light, infrared)


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## s0high (Aug 1, 2009)

If you guess actually want to get down to how plants use light you must look into something called umol. It is a special formula that you can never expect to understand that takes most aspects of a plant to figure it maximum amount of usable light.

There is much research that needs to be done on weed before we know what its umol is. If you want to learn about how umol works then look up how much light is required for lettuce to grow. I warn you, its like the red of blue pill in the matrix. Itll fuck yo mind up.


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## mj320002 (Aug 1, 2009)

Lumens don't add. The reason the t-5 setups your looking at say 20,000 lumens at 5,000 lumens per bulb is because the 5,000 lumens is spread out over a larger area. If you took those four bulbs and put them next to each other it wouldn't make the area directly below any brighter. Multiple bulbs allows you to cover a larger area more effectively. If you want brighter light though you will need more powerful bulbs or better reflectors. 

I think this principal applies to PAR as well but I'm not entirely sure. 




s0high said:


> If you guess actually want to get down to how plants use light you must look into something called umol. It is a special formula that you can never expect to understand that takes most aspects of a plant to figure it maximum amount of usable light.
> 
> There is much research that needs to be done on weed before we know what its umol is. If you want to learn about how umol works then look up how much light is required for lettuce to grow. I warn you, its like the red of blue pill in the matrix. Itll fuck yo mind up.


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## T.H.Cammo (Aug 1, 2009)

Don't you just love it!

Of the six, definitive, "Limiting Factors" light is (without a doubt) the most complicated and hardest to understand. I think that's why most people just "accept" a few "basics" and pretend to understand the rest. Yes, what you heard is true - "Lumens are for Humans" and they're a piss poor measurement for a grow light. However - - - -

Lumens measure the appearant brightness of a light source as percieved by the human eye. Our eyes are most sensitive to green light, so the green portion of the light spectrum produces a high ratio of "lumens". The problem with lumens is that plants, in general, don't absorb green light they reflect it - thats why they're green in appearance. Plants actually use more red light and blue light, which both produce a lower ratio of lumens. Now we get to PAR light:

In the "Illumination" business lumens are important because they can indicate how bright a lamp is (even though it puts a premium on green light). PAR stands for "Photosynthetically Active Radiation, it is only interrested in those parts of the light spectrum that a plant actually uses. So, basically, you can think of green light as non-PAR light - as opposed to LED grow lights which are virtually 100% PAR lights!

Like BigBudBalls said "They do and they don't" (add up).
"They do" in the sense that 2 identicle lights will allow you to grow twice as big of an area.
"They don't" in the sense that 2 identicle lights wont produce twice the intensity, they will just give you "more of the same". Think of it this way - if you have a quart of water @ 106 degrees f. and you add another quart @ 106 degrees f., you don't end up with boiling water! You just end up with twice as much water at the same 106 degree f. temperature (intensity). OK?

Big Bud Balls also said "Light diminishes further it travels". This can't be stressed enough!!! Most growers (well, at least, some growers) generalize this to mean "Keep the light "close" to the plants, if you can, sort of". The harsh reality is "The Inverse Square Law (of light)", this is pure Psysics and it's right out of the book, it goes something like this: As the distance between the light source and the plant doubles, the energy of that light is reduced by a factor of 4 (double the distance equals one fourth the light energy!). Think about that for a moment! That is a huge drop in the amount of light your plants will receive because the formula starts at a rediculousely small distance.


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## potsticker (Aug 1, 2009)

The lumens add they just don't add perfectly. More lights close together will increase the light directly below any of them - as opposed to only having one light. However as light diminishes you won't have the same penetrating power as mj320002 pointed out but you will hit the top buds from more angles with more light.


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## smppro (Aug 1, 2009)

mj320002 said:


> Lumens don't add. The reason the t-5 setups your looking at say 20,000 lumens at 5,000 lumens per bulb is because the 5,000 lumens is spread out over a larger area. If you took those four bulbs and put them next to each other it wouldn't make the area directly below any brighter. Multiple bulbs allows you to cover a larger area more effectively. If you want brighter light though you will need more powerful bulbs or better reflectors.
> 
> I think this principal applies to PAR as well but I'm not entirely sure.


sorry there is a thread on here of somebody comparing the light directly under 1 cfl vs 3 with a light meter and the 3 made it more intense


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## BigBudBalls (Aug 2, 2009)

potsticker said:


> The lumens add they just don't add perfectly. More lights close together will increase the light directly below any of them - as opposed to only having one light. However as light diminishes you won't have the same penetrating power as mj320002 pointed out but you will hit the top buds from more angles.


If using all 2000 lumen lights, no matter how many you add, you will never pass 2000. (adding in a mountain of them light may cause the temp to go up enough to effect the sensor giving inaccurate readings.)

ceestyle did a whole thing on this (its a stickie) but never proved exceeding the base lumen value.

You have volume and force. Adding more lights in parallel is adding more volume, not force (in series would add force)
Intensity would = force.


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## BigBudBalls (Aug 2, 2009)

smppro said:


> sorry there is a thread on here of somebody comparing the light directly under 1 cfl vs 3 with a light meter and the 3 made it more intense


Yea ceestyle, but never showed *over* base lumens. (it was just getting more of the 'lost' lumens further away.

Al B . Fuct Also did it. 1 vs 2 and no change.

Diff in the testing is that Cee had the meter a foot or so away, Al B had it right up at the source.


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## grobofotwanky (Aug 2, 2009)

Great post T.H.Cammo


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## smppro (Aug 2, 2009)

Ok i wont argue, how come nobody has figured out the smallest amount of lumens spread over an area to achieve nice bud, i can personally say that only 2600 lumens spread out will grow nice sized dense buds.


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## TeaTreeOil (Aug 2, 2009)

mj320002 said:


> Lumens don't add. The reason the t-5 setups your looking at say 20,000 lumens at 5,000 lumens per bulb is because the 5,000 lumens is spread out over a larger area. If you took those four bulbs and put them next to each other it wouldn't make the area directly below any brighter. Multiple bulbs allows you to cover a larger area more effectively. If you want brighter light though you will need more powerful bulbs or better reflectors.
> 
> I think this principal applies to PAR as well but I'm not entirely sure.


This is wrong. And really, it's a glaringly obvious contradiction. How will a reflector improve anything but more light emitting sources themselves won't? Ugh!



T.H.Cammo said:


> Don't you just love it!
> 
> Of the six, definitive, "Limiting Factors" light is (without a doubt) the most complicated and hardest to understand. I think that's why most people just "accept" a few "basics" and pretend to understand the rest. Yes, what you heard is true - "Lumens are for Humans" and they're a piss poor measurement for a grow light. However - - - -
> 
> ...


He was doing so well.... Sigh. But apparently he thinks(according to the analogy about water temperature) that adding more bulbs won't increase heat what so ever? Shocking! it's a bad analogy anyway -moving on.

Lumens do add. That's what's called total lumens. Lumen output is a measure of a bulb. A bulb is the same amount of lumens whether next to another bulb, or it's on another planet all by itself . Distance doesn't mean anything, more or less bulbs don't change this. A bulb's lumen rating is the bulb's lumen rating no matter what.

Lux, lumens per sq meter, will change depending on how many bulbs are used. This is obvious. If you take multiple flash lights, shine them into one spot, it's obviously a brighter spot than one of them alone. Does this make any of the flash lights brighter? Of course not! Take a mirror or something else highly reflective, shine your room's light(I assume your room has a light bulb, otherwise use the sun) rays onto the wall, there's a brighter spot, and it moves around the room according to the angle of the reflective material relative to the light source. Ever burn something with a magnifying glass? Again, focusing light, MULTIPLYING it several fold.

Ok, we've proven light can be additive/multiplicative. Moving on...

We're talking about WHERE LIGHT IS STRIKING, not WHERE LIGHT IS COMING FROM. Does the magnifying glass make the sun magically brighter? No, it does no, only SELECT STRIKING rays emanating from it(that hit the magnifying glass, of course!) -not the sun itself. Where multiple sources are all STRIKING becomes brighter, it doesn't 'travel backwards' to the source and magically make the source brighter -that's ridiculous! But this is apparently the argument used to claim light is not additive.

Lux is a more complex notion than lumens. But basically, two equal light sources, equidistant from the striking point(and equal/opposite incident angles) your lux would double. Does this make either of the bulbs brighter? No, of course not -ridiculous. Because at 1 foot away, the bulb is already 16 times less intense than it is at 3 inches(approximately). And at 3 inches it's 16 times less intense than it'll be at 0.75 inches(approximately). However, having two bulbs, equidistant and equiangular from these 'test points', these measurements would be very near doubled(especially the further away).

Most bulbs aren't considered true point sources, so the mileage will vary. Moving on.

Nothing is going to make the bulb any brighter. It's not a matter of WHERE LIGHT IS COMING FROM, but WHERE LIGHT IS GOING TO. Are two fluorescent tubes capable of twice the lux? Yes! But not at 1 millimeter away! That's the peak lux zone of the bulb. No amount of bulbs are going to produce a lux beyond that of the bulb itself(measured at the surface of the bulb)! Of course this doesn't matter, do your lights touch the plants? Of course not! Or at least probably not. And by the time it travels from .075 inch to 1 foot, it's now 16*16 times(that's 256 times) less intense, anyways. But with two bulbs, that could be nearly 128 times(half the decay), 4 bulbs, 64 times(nearly 4 times brighter at 1 foot!), which is why fluorescent tubes are often used in 2 or 4 tube fixtures.

What more bulbs will do is increase the volume of usable light, and increase the intensity(density of photons) within that volume, assuming they're all illuminating the same volume.


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## bakeddude (Aug 2, 2009)

Great post TeaTree.
Clears it up.


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## jimmyc (Aug 2, 2009)

You know it's funny you guys are having this discussion in the same forum that I posted the answer. Enjoy!


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## doobnVA (Aug 2, 2009)

Whoa, I left this thread for 12 hours and suddenly there are all kinds of answers! Hooray!

Just for stopping by, everyone gets a +rep (oooooh, aaaaaaah)!

Anyway, I read that other thread, jimmyc, and I must admit the part with the charts and graphs was a little over my head. I haven't had my morning coffee yet, so I'll revisit it when I'm closer to fully awake than I am now.

Someone there says that floros have the most usable light for plants? I can only hope this is true, as I'm a floro lover and have been looking for any excuse to purchase additional bulbs!

Someone there also says that a lower lumen rating on a bulb is indicative of a better light for plants? Something rings true about this to me. since "lumens are for humans" (teehee), and measure more of the green light than anything else (which plants can't use) it seems to make sense that a lower lumen output bulb probably has more light in the blue and red ends of things which is what plants use.

Now, I'm also under the impression that LED grow lights typically don't even offer up their lumen output, and If you've ever seen LED grow lights in action you'll know that they don't appear "bright" in the way we expect from a grow light. Here's a quote from an LED related site:

The most accurate unit 
of measurement for comparing grow lights is the micro Einstein, which measures how many photons of light strike an area per second

Then they go on to say that all types of grow lights (except the ones they sell, of course) emit large amounts of unusable light. 

Does anyone know what the lumen output of an LED grow light is? Has anyone seen a successful grow that used only bulbs with a low lumen output (13W CFLs, for instance)?


EDIT: I've given out too much rep in the past 24 hours... how long do I have to wait before I can hand out more?


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## mj320002 (Aug 2, 2009)

Yeah so lumens aren't really a good measurement of how good a light is at growing. We already knew that and that was a nice little read Jimmyc. 


That article however doesn't really address whether or not light adds. Even though we are talking about lumens adding the same thing seems to apply to light in all spectrums including PAR. I think the place the disagreement comes from is we are thinking about the question differently. Some people say it does because the light volume increases so you can cover a larger area with more bulbs. The ones who say it doesn't myself included are saying that it doesn't add because the light isn't actually brighter at the source. 

In order to make this information useful we need to know how much light and in what specific spectrums an mj plant can use. PAR is useful but that article also spoke of accesory pigments which are beneficial as well. I personally think this is where LED's fall short. Currently they are too limited in the spectrums being produced along with a possible lack of intensity. Not because they can't produce the spectrums but because people are focusing on to narrow of spectrums. 

I think I might have rambled a bit but I hope you get what I'm saying.





doobnVA said:


> Whoa, I left this thread for 12 hours and suddenly there are all kinds of answers! Hooray!
> 
> Just for stopping by, everyone gets a +rep (oooooh, aaaaaaah)!
> 
> ...


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## fish601 (Aug 2, 2009)

the sun seems to work well for me.. who would of thought?


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## mindphuk (Aug 2, 2009)

mj320002 said:


> In order to make this information useful we need to know how much light and in what specific spectrums an mj plant can use. PAR is useful but that article also spoke of accesory pigments which are beneficial as well. I personally think this is where LED's fall short. Currently they are too limited in the spectrums being produced along with a possible lack of intensity. Not because they can't produce the spectrums but because people are focusing on to narrow of spectrums.
> 
> I think I might have rambled a bit but I hope you get what I'm saying.


No, you said it perfect. This is something I brought up in one of the LED threads. I think that an LED array may need to have 3, 4 or even 5 different lamps to cover all of the spectrum necessary. However, even if we can find the right combination for flowering is found, the next hurdle is intensity. I think most people use at most 5w per lamp. If that can be bumped up to maybe 10 or even 15w, maybe we can finally see some nice buds.


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## mindphuk (Aug 2, 2009)

TeaTreeOil said:


> Mindphuk is another person who makes up bullshit, and doesn't have a clue. He's on my ignore list.


You are so full of shit. You haven't shown one thing I said was incorrect. Talk is cheap, why don't you back it up with something substantial. I'd really love to see where I said something incorrect wrt physics.


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## bigtomatofarmer (Aug 2, 2009)

Thank you tea tree oil for trying to help these stoners.


But sometimes a picture is worth 1000 words









Also, remember that High Pressure Sodium is the most efficent bulb on the market. Well, except LED. 
But still, it is more efficent in $$$, and has better light coverage.

*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


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## TeaTreeOil (Aug 3, 2009)

Wow. Imagine that. You say someone is full of shit, when they're obviously full of shit, and the post vanishes. While the bullshit remains....

This site is a detriment to all horticulture.


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## mindphuk (Aug 3, 2009)

TeaTreeOil said:


> Wow. Imagine that. You say someone is full of shit, when they're obviously full of shit, and the post vanishes. While the bullshit remains....
> 
> This site is a detriment to all horticulture.


Yes, too bad they try to keep it civil here and won't allow unprovoked personal attacks on this board. Imagine all the fun we could have.


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## fenderbender1201 (Aug 3, 2009)

a good way to get GREAT light on a plant that ive found recently is to build a screen around a CFL bulb and keep in milimeters away from the bud site

the screen keeps all vegetation from hitting the bulb, and keeping the great light output of a CFL.


i imagine a screen on multiple bulbs all around the bud sights mm's away would be much more effective then any HPS light... no?


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## doobnVA (Aug 3, 2009)

bigtomatofarmer said:


> Thank you tea tree oil for trying to help these stoners.
> 
> 
> But sometimes a picture is worth 1000 words
> ...





Now I'm confused again. Didn't we already decide that lumen output has no bearing on how good the light is for plants? If that's the case, then a higher lumen per watt bulb isn't necessarily the best bulb for growing plants, right?


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## 110100100 (Aug 3, 2009)

doobnVA said:


> Now I'm confused again. Didn't we already decide that lumen output has no bearing on how good the light is for plants? If that's the case, then a higher lumen per watt bulb isn't necessarily the best bulb for growing plants, right?


Right, lumen have nothing to do with how a plant sees light.


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## jimmyc (Aug 3, 2009)

Some clearing up is in order evidently. No, light does not 'add'. Adding more bulbs to your garden will only help to ensure that more area gets what ever wattage you want. For instance, if you have a 400 watt HPS in a 8x8 area you can be sure that not all of that 64 square feet is getting 400 watts. However if you add another 400 watt HPS you don't now have 800 watts, you have 400 watts over a larger area.
As for HPS being the most efficient bulb well that just plain false again as is explained in another post I made to this forum, Ceramic Metal Halide is actually the most efficent. It's only draw back is wattage, Phillips currently only makes 400 watters but is in the process of retrofitting a few factories to make higher wattages.


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## sweetsmoker (Aug 3, 2009)

As for HPS being the most efficient bulb well that just plain false again as is explained in another post I made to this forum, Ceramic Metal Halide is actually the most efficent. It's only draw back is wattage, Phillips currently only makes 400 watters but is in the process of retrofitting a few factories to make higher wattages.[/QUOTE]
i have purchased a 4 x 250w cfl hood, this light is 100% p.a.r and can be lowered to within inches of the plants,, was wondering if this would be considered better than a hps due to these factors, or do u believe a hps wud outshine this unit... if like myself u believe the hps 2 be better, then surely it is the photons that are more important to the plant than par as hps has more photon output but only 15% par. mmmmm just another spanner in the works for us all 2 contemplate wat u lot think... im gunna giv it a go anyways and find out here a pic of the unit


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## mindphuk (Aug 3, 2009)

jimmyc said:


> Some clearing up is in order evidently. No, light does not 'add'. Adding more bulbs to your garden will only help to ensure that more area gets what ever wattage you want. For instance, if you have a 400 watt HPS in a 8x8 area you can be sure that not all of that 64 square feet is getting 400 watts. However if you add another 400 watt HPS you don't now have 800 watts, you have 400 watts over a larger area.
> As for HPS being the most efficient bulb well that just plain false again as is explained in another post I made to this forum, Ceramic Metal Halide is actually the most efficent. It's only draw back is wattage, Phillips currently only makes 400 watters but is in the process of retrofitting a few factories to make higher wattages.


Even though 2 400w lamps don't give the same output as an 800w, where the two overlap, there will be an increase in light energy. This was proved very early on that light acts like waves and that you can even get interference patterns when the two point light sources combine, the crests are bigger and the troughs cancel each other out. 

This is very easy to demonstrate with a lux meter. The area of overlap is brighter and registers more lux than a single lamp will produce at a given distance.


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## TeaTreeOil (Aug 4, 2009)

jimmyc said:


> Some clearing up is in order evidently. No, light does not 'add'. Adding more bulbs to your garden will only help to ensure that more area gets what ever wattage you want. For instance, if you have a 400 watt HPS in a 8x8 area you can be sure that not all of that 64 square feet is getting 400 watts. However if you add another 400 watt HPS you don't now have 800 watts, you have 400 watts over a larger area.
> As for HPS being the most efficient bulb well that just plain false again as is explained in another post I made to this forum, Ceramic Metal Halide is actually the most efficent. It's only draw back is wattage, Phillips currently only makes 400 watters but is in the process of retrofitting a few factories to make higher wattages.


Light adds. I proved it a few posts ago. Work on your reading comprehension.


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## TeaTreeOil (Aug 4, 2009)

mindphuk said:


> Even though 2 400w lamps don't give the same output as an 800w, where the two overlap, there will be an increase in light energy. This was proved very early on that light acts like waves and that you can even get interference patterns when the two point light sources combine, the crests are bigger and the troughs cancel each other out.
> 
> This is very easy to demonstrate with a lux meter. The area of overlap is brighter and registers more lux than a single lamp will produce at a given distance.


OH YOUR GOD! You finally see the light.


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## mindphuk (Aug 4, 2009)

TeaTreeOil said:


> OH YOUR GOD! You finally see the light.


I really think you have me confused with someone else. Our disagreement was the properties of aluminum metal such as in a reflector vs. aluminum foil. I have never held any other position on light and was one of the first ones in one of your early posts about light to recommend to the doubters to buy a cheap light meter. 

As any good scientist knows, vigorous debate and defense of ones position is fundamental to progress. I have been at conferences where it looked like fistfights would break out. However, I have never refused to listen to what a colleague has to say and would never consider someone worth of ignoring if they disagreed with me. You may not remember, but I repped you early on when you first joined, there are many topics we agree on. I really think you were being quite childish when you decided you had to ignore me because we didn't see eye-to-eye on a single topic.


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## jimmyc (Aug 4, 2009)

I was under the assumption they would be inline and overlap would be minimal. It would stand to reason that light overlap would be a bother to any grower because they cause irregular canopies. Not to mention if you're looking for more light through light overlap just get a higher wattage. Cermaic Metal Halide for the win over High Pressure Sodium!


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## bigtomatofarmer (Aug 4, 2009)

I read your other thread about ceramic metal halide, but I failed to see where you mentioned the watt/lumen output???

I understand your point about a wider spectrum range, but my electric company charges by the watt. 

Also, how often do those CMH bulbs go out? My HPS has been kickin for 2 years now. Actually, Im glad you reminded me, I should change that sucker out haha


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## plutomoney (Mar 17, 2010)

bigtomatofarmer said:


> Thank you tea tree oil for trying to help these stoners.
> 
> 
> But sometimes a picture is worth 1000 words
> ...



Let me get you pic right 50000/10=5000
5000/54=92.6

so its 92.6 lumens per watt for a t5ho ist that more than the Mh or is that a typo in the pic


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## plutomoney (Mar 17, 2010)

i would love to have a nonceramic mh bulb thats 50k lumens i think a mh salemans made that chart


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## macrael (Mar 17, 2010)

i am not an expert but when i bought my *SUNBLASTER T5 24 Watt High Output - 6400K(*http://sunblasterlighting.com/t524.html) was supposed to be equal to 125w or 150w bulb but i just noticed that degrees kelvin is more then most hps or metal halides most range from 2100 to 5500deg. k. maybe thats why my babies are so pale hmmm. also im am not an expert like i said i dont know if there ceramic or not but almost all the mh lights have way more then 50k lumens from the chart that i seen from que pousse but then theres another section where they don t even show the lumens (there marked with a ?) i am not saying your wrong just stating info that i found


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## macrael (Mar 17, 2010)

plutomoney said:


> Let me get you pic right 50000/10=5000
> 5000/54=92.6
> 
> so its 92.6 lumens per watt for a t5ho ist that more than the Mh or is that a typo in the pic


 i think they went with options that best suited there needs cause my t5 is around 2000 lumens and its 24w comes out to 83.3 lumens /w


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## plaguedog (Mar 17, 2010)

The reason why they show the lumens per watt is to show efficiency, not the power of the bulbs. So yes, t5 floro are more efficient with lumen per watt then MH.


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## plutomoney (Mar 17, 2010)

macrael said:


> i am not an expert but when i bought my *SUNBLASTER T5 24 Watt High Output - 6400K(*http://sunblasterlighting.com/t524.html) was supposed to be equal to 125w or 150w bulb but i just noticed that degrees kelvin is more then most hps or metal halides most range from 2100 to 5500deg. k. maybe thats why my babies are so pale hmmm. also im am not an expert like i said i dont know if there ceramic or not but almost all the mh lights have way more then 50k lumens from the chart that i seen from que pousse but then theres another section where they don t even show the lumens (there marked with a ?) i am not saying your wrong just stating info that i found



Im using T5's grow to harvest and that 24w t5 is not a high output its a regular t5 t5ho are 54w. The temp range is for the spectrum of light used light is a different colors beacuse of the kelvins the t5ho are a little bit more not by much than regualr t5's


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## plutomoney (Mar 17, 2010)

plaguedog said:


> The reason why they show the lumens per watt is to show efficiency, not the power of the bulbs. So yes, t5 floro are more efficient with lumen per watt then MH.



I was trying to show the picture is wrong 90 lumens per watt and 400 watt is like 36k lumens not near 50k lumens at the coop near me they have a grow by grow with MH and t5ho(for Veg) and the t5 has tighter nodes seems denser the experiment was done with indicas and the Mh had the same results as a 8 bulb t5ho on the sativas the t5 had an advantage. Im glad I bought the t5s because a week ago i seen the comparison. Im not doggin a mh but that pic makes it seem like its the best since sliced bread.


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## macrael (Mar 18, 2010)

plutomoney said:


> Im using T5's grow to harvest and that 24w t5 is not a high output its a regular t5 t5ho are 54w. The temp range is for the spectrum of light used light is a different colors beacuse of the kelvins the t5ho are a little bit more not by much than regualr t5's


sorry just went to check on the site of the type of flor. that i am using i put a link in my other post and it states that go check your self i haven t tested it but it is written there that the 24 and the 54 w have the exact same degrees k. the only difference was in lumens take a lookat the site there suppsed to be a new type on the market
here it is again and you can check between the three different sizes they have in ho floros http://sunblasterlighting.com/t554.html


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## macrael (Mar 18, 2010)

i just use what i have theres many different methods that do work. if theres somebody that drinks coke there whole life you think you can get them to change to pepsi then theres other people that drink a variety of things not just one refreshment. i havent seen anybody produce huge colas with leds or florescents or cfls but that doesn't mean i dont believe it can t be done who knows maybe leds will be the future but for now hps and mh and ceramics produces the best results that i have seen another thing i belive is that most mh are better for vegging and most not all hps are better for flowering and most ceramics are kind average between both worlds of light although theres lots of things that come into play here such as different producers(companies) and different combinations of light spectrums there is not one bulb that can completely imitate the sun that i know of. i was under the impression that the more lumens the better ? or is it more lumens =to more heat. i give up i aint a scientist im just going to have fun growing my little buddies lol cheers everybody


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## plutomoney (Mar 18, 2010)

macrael said:


> i just use what i have theres many different methods that do work. if theres somebody that drinks coke there whole life you think you can get them to change to pepsi then theres other people that drink a variety of things not just one refreshment. i havent seen anybody produce huge colas with leds or florescents or cfls but that doesn't mean i dont believe it can t be done who knows maybe leds will be the future but for now hps and mh and ceramics produces the best results that i have seen another thing i belive is that most mh are better for vegging and most not all hps are better for flowering and most ceramics are kind average between both worlds of light although theres lots of things that come into play here such as different producers(companies) and different combinations of light spectrums there is not one bulb that can completely imitate the sun that i know of. i was under the impression that the more lumens the better ? or is it more lumens =to more heat. i give up i aint a scientist im just going to have fun growing my little buddies lol cheers everybody


The 24w are the 2 footers you are right different strokes for different folks the temperture is just for the spectrum of light given off. And to get huge colas you need a smaller light source because a 1kw mh thats 18' long wont concentrate the light for huge colas the heat in kelvins are just for spectrum range sorry about the miss spelling english is my 3rd language. Funny because i was born here in the states.


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## VividDane (Oct 19, 2010)

according to this information there is no general conversion factor between lumens and PAR. That is if im reading it right.

I posted this in another thread but I think it fits in here just as well.

The chart below will give people a good impression of how much PAR is being emitted from various std. light-sources.



> *How can I evaluate the effect of different light sources on plant growth?*
> 
> The Photosynthetically Active Radiation (PAR) measure of radiant power is important in evaluating the effect of light on plant growth.
> 
> ...


Source: http://openwetware.org/images/e/e8/Conversion_lux.pdf

The way I understand the note of no general conversion factor is that the PAR emitted can not be sized by a given lumens output, instaid you have to calculate the total moles for the grow-area space vs. light-source, wich is somewhat different from the way we measure lumens. So, no direct relation between lumen and PAR. Please correct me if I'm misreading things.


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## bigv1976 (Oct 19, 2010)

Ok so if lumens dont add up the all the people growing with 26 watt CFLs are only giving there plants however many lumens come from 1 bulb?


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## Kphlash (Oct 19, 2010)

bigv1976 said:


> Ok so if lumens dont add up the all the people growing with 26 watt CFLs are only giving there plants however many lumens come from 1 bulb?


Get lumens out of your head as the main factor, look for PAR. Lumens can also be equated with heat. More lumens = more heat

lots of analogies have been used basically 1 candle reaches 40ft, 2 candles next to each other will just make those 40ft brighter-it will not make the light go 80ft 

so they amplify the space they are in, but each bulb has a maximum reach, space them out and you will cover more area with same energy (cept where they cross beams), put them together and the light will be brighter in that smaller area

Everyone is saying the same basic thing, but arguing over slight semantics. Basically, the farther from the light, the less energy the plants receive, the higher lumens generally means you can basically keep your light at a farther distance to give them same energy (you really have to because of heat) again tho, lumens arent worth much to plants so it makes little difference. 

I would much rather have my HID higher up covering all plants and use HO T-5's, CFL's and or LED on the sides to help cross light beams and make sure everything is getting ample light. a light meter is nice to have too-not too expensive, relatively speaking of course lol. camera shops have nice ones for cheap

Basically though, get these old ideas out of your head, I have had great results with LED's, but only as supplemental because of the narrowed spectrum-but combining them with HID is amazing, uses less energy and not as toxic to mother nature as CFL, and fills the gaps of most HID spectrum. 

Personally my fave setup for an all in 1 tent (veg n flower if u need)if you can beat the heat, is 1-1000w Hortilux BLUE MH (want a 600w but not available n 400 is too weak for my area's) 3-HO T-5's along each side of tent (hang vertically on walls at lower nodes), and depending on the $$ some LED's from the top, prob i have is them shading the HID some, but i keep them in the corners mostly and they stay outta way since the HID usually has weakest energy in corners, 1 heavy exhaust w/ can fan, 2 wall mount fans and you can get an easy QP off a plant. my temp stays 60-75F (15degree drop at night)

http://www.eyehortilux.com/blue.html check this bulb out - not trying to plug it, but best spectrum i have seen on an HID and results are impressive


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## Nubby Tubbs (Oct 19, 2010)

hes full of poopoo bigv. if you have 2 100 watt bulbs you have 200 watts of light. double the lumens. thats why its twice as bright. think about it.


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## bigv1976 (Oct 19, 2010)

Can someone link a youtube vid on the subject maybe? I have seen a test where the guy had a light meter and I think I remember that lumens did go up when bulbs where added but not by double. I wanna say that it worked like 1 5000 lumen bulb was 5000 lumens but 2 was like 7200.


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## VividDane (Oct 19, 2010)

bigv1976 said:


> Ok so if lumens dont add up the all the people growing with 26 watt CFLs are only giving there plants however many lumens come from 1 bulb?


Correct, inorder to increase the PAR (where chlorophyll a & b is being stimulated) there has to be an increase in the intensity of the light, not the volume of it. A CFL emits more PAR per watt then a HPS does, but the most powerful CFL I've come upon is a 300 Watt 9U. The intensity of this CFL is claimed as an alternative to a 600 Watt HPS, but i wouldn't count on it. I might buy a quantum-meter that can directly measure the PAR-levels at any given point of a grow-room (or lamp) and compare this and other bulbs to a 600W HPS. I own quite a collection and I don't seem to be able to find other people who has done this, other then lamp/led-lamp producers, and their word just isn't good enough IMO, since they could easily give a fair reference or suggestion to these values in the product datasheet/description. Most lamp-producers doesn't give any other info then watts consumed and lumens emitted at the very outer tip of the bulb-glass.



> *SOURCE
> Photosynthetically active radiation (PAR), measuring radiance in watts, is much better than photopic units (lumens or lux) or radiometric units (watts or watts/m^2).* PAR is a mesaure of lamp output in the spectrum that is actually useful to the plants. However, this data is only available for a small number of lamp models. An additional limitation is that the PAR watt treats all wavelengths between 400 and 700nm equally, but all wavelengths within that range are not equially effective for plant growth. Despite these limitations, PAR efficacy (PAR watts emitted/watts consumed) is a decent indication of efficiency for horticultural lamps. PAR irradiance can be measured using a spectroradiometer (not cheap!).


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## VividDane (Oct 19, 2010)

bigv1976 said:


> Can someone link a youtube vid on the subject maybe? I have seen a test where the guy had a light meter and I think I remember that lumens did go up when bulbs where added but not by double. I wanna say that it worked like 1 5000 lumen bulb was 5000 lumens but 2 was like 7200.


doesn't matter if the lumens goes up, this would only apply to office-lighting etc. _NOT_ grow-lighting. Lumens is a measure of light that stimulates our brain through our eyes. Plants needs a different kind of light emitted at a different wavelength in order for chlorophyll a & b to be stimulated into photosynthesis. Lumens is BS in growlighting.


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## VividDane (Oct 19, 2010)

a CFL with low lumens level most often has a higher emission of PAR then a similar CFL of equal watts and higher lumens output. This is because most CFL's are produced and tuned for a higher lumens level. This is also the reason why expensive CFL-lamps for plant-growing tends to have a lower lumens-output then similar noname or cheaper types.


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## marti221 (Nov 6, 2010)

Hello.

From the info that I have gathered while researching light and how its used by plants I can say I do know a quite a bit. However I wouldnt dare call myself an expert.... Not yet at least. hehe. First, we are going to start off with the basics. I think we all know that light is needed throughout the entire lifespan of cannabis (at least I hope I think that most of us here are interested in getting the most massive, dense, stinky bud we can while trying to stay cost efficient. (I feel like not enough people take cost into effect when giving their responses and opinions, and seeing how this is pretty much the main reasons we are all asking these questions, you would think people would think before posting simple high priced solutions. " Do two or 3 $30, 150w hps lights accomplish as much as a 250w or 400w HPS (costing usually minimum $100-$150)? UUUUUUGGGG JUST GO BUY A 600W HPS $300.... <---- Not a helpful response, if i had money to drop on a nice new hps ballast, then I probably wouldnt be asking if $30 lights would work, Thank you haha). 

Anyway... Most of us also can agree that the specific kinds of light (wavelengths in nanometers-nm and specific colors-red,blue,green..., color temperature in degrees Kelvin-K) needed at the different stages of development are also widely accepted. Knowing the wavelengths of light needed for both vegetation stage and flowering is one of the many keys to a successful grow. Cannabis like other plants uses primarily blue light (apprx 450nm, or 5500-6000k) with little red during vegetation, and red light (apprx 650nm, or 2200K) with little blue during the flowering stage. Now that we know the kinds of light needed, lets discuss the light sources that will create these ever so important wavelengths. First, lets discuss cfls, though they are sufficient and even preferred in many cases for veg, they are not optimal during the flowering stages due to the lack of "intensity." While I have always been told (and constantly see in posts) that more light equals bigger yeild and thicker, denser buds. This brings me to my main question... What is "more light"? 

The general unit of measurement you are going to see advertised by light bulb companies are called Lumens. Lumens, in short, measure the amount of light seen by the human eye. As you can imagine, this isnt the best way, or even a good way to measure light for plants. Why you ask?...We "see" or use in the plants case, light differently than what the plant uses for photosynthesis. The human eye is much more sensitive to some colors of light (different colors are caused by different wavelengths of light, red= apprx 650 nm, blue=apprx 450nm), primarily yellow. Plants dont even use the green light viewed by us. This is how plants get there green color, because they are reflecting the unused green light . For example... We now know plants dont use green light, they use or absorb blue and red light predominantly. This means that any light source giving off green light, yellow light remember because the human eye is more sensitive to yellow light (though plants do absorb little yellow/orange light for photosynthesis) or any other color not being absorbed by the plant, is still represented in the "total lumen output" on the light package. So when a light bulb claims to have a certain amount of lumens, only a small percent is actually being used by the plant. This is also why you may see multiple cfl bulbs of the same wattage but with different Kelvin temperatures (another way of representing light, 2200k=red light for budding, 5500k=blue light for veg) with names like "soft while "or" cool blue,"have quite a big descrepancy in total lumens. 

PAR is a much more effective way of measuring light because basically, (without all the scientific lingo) it measures the amount of light actually useful to the plant (as I said, red and blue light predominantly). As for " adding light," from what I have read you cannot technically add lumens or PAR (basically you cannot increase the intensity of the light by adding wattage). Which does make sense if you think about it. Two 250w hps lights will not be giving your plants twice the intensity, just twice the light. However the one thing that I havn't really seen people talk about is photons. Don't get me wrong, I am no scientist. I have taken a few chem, bio, cell bio courses for my major but i no way am I an expert. Anyway... photons. Photons are the individual "particles" of light that are given off by lamp or any other source of light. Plants use the light energy (photons) and convert it into chemical energy through chlorophyll via photosysthesis (Im sure we all remember this from elementary school).So this got me thinking... We do know that neither lumens or PAR can be "added" together to form higher intensity light. My theory is that plants even when flowering may not necessarily need this increased intensity, but just more photons. This is where I need to do some more research but my thoughts are that though PAR cannot be added, photons seem like they should. I dont see how adding 2 lights closely together wouldnt increase the amount of total photons absorbed and/or present. Like I said I am no expert. Increased intensity in light may increase the amount of photons in a given space leading to larger and denser buds, but I dont know. I havent really come across any posts explaining the million dollar question... WHY DOES INCREASE IN LIGHT INTENSITY LEAD TO LARGER DENSER BUDS???? or is it even the "Intensity" that causes this? or What technically is light intensity?


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