CFL Light Tutorial

[420warriors]

Hey Roseman, I was looking at a box for one of those lights with reflector. It's an outdoor flood with a 100w, 6500k CFL. It listed the lumens at around 10,000 but on bottom of box said that was perceived lumens (what it looks like to the human eye) and said actual output was 6700lu. Do you have any input on this, or know if other CFLs are rated this way? I'll have to go back and read the box for more accurate info and what the rating was called.

 

[Lil Neutrino]

The difference between the lux and the lumen is that the lux takes into account the area over which the luminous flux is spread. A flux of 1,000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1,000 lux. However, the same 1,000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux.

Lux - Wikipedia, the free encyclopedia

The probable reason for it having the two ratings is that it is a floodlight and therefore has a different application in normal uses. A floodlight is used mostly to illuminate a certain portion of a larger object and often at a bit of a distance. The intensity that we humans perceive from the output source (the light) is the actual lumens of the bulb. Lighting engineers and designers can use that rating to help achieve pre-calculated lighting intensities, next time you see a commercial building or whatever lit up with spotlights at night you can be sure that those bulbs and reflectors were not chosen at random, somebody had some fun crunching numbers and looking at radiance charts (or whatever they're called) to figure out that effect ahead of time.

Lumens are what we use to rate the intensity of the light source.
Lux is used to rate the intensity of the light over a specified area

PAR (Photosynthetically Activated Radiation) wattage is what we really care about, check that, it's what the plants really care about. This is because the plant are on the receiving end of the photons, are at a distance from the light source, and require certain wavelengths of light to have proper "nutrition". It is a measure of the irradiant light, basically the light intensity once it hits the target surface. Easier to find this rating for HID lights than CFL's but then again HID's are often used for growing plants I have yet to see PAR on any locally purchased CFL bulbs but that's because regular CFL applications don't usually concern themselves with growing plants.

Light and Plants

 

[Roseman]

Hey Roseman, I was looking at a box for one of those lights with reflector. It's an outdoor flood with a 100w, 6500k CFL. It listed the lumens at around 10,000 but on bottom of box said that was perceived lumens (what it looks like to the human eye) and said actual output was 6700lu. Do you have any input on this, or know if other CFLs are rated this way? I'll have to go back and read the box for more accurate info and what the rating was called.

That I am not 100% sure of, but I am 100% sure of ALL fluorescent bulbs put out no less than 60 and no more than 70 lumens per watt, so a 100 watt bulb could not put out 10,000, it would be nearer to 6000 to 7000 lumens.

I 'd go by the actual output.

 

[Lil Neutrino]

Good info Roseman. I might also add that there are an "initial" rating and a "mean" rating for CFL's that has to do with their intensity when new (afaik) versus after they age a bit. Marine aquarium keepers have to change their lights out on a regular basis (roughly yearly iirc, maybe not so often anymore) for the same reason. Light intensity becomes reduced and possibly some color shift in the output spectrum. Of course our light are usually on for much longer periods of time than aquarium keepers but I'm also not sure of roughly when CFL's begin to lose their "new" characteristics...might be good for years, might not *shrugs*

 

[Roseman]

Good info Roseman. I might also add that there are an "initial" rating and a "mean" rating for CFL's that has to do with their intensity when new (afaik) versus after they age a bit. Marine aquarium keepers have to change their lights out on a regular basis (roughly yearly iirc, maybe not so often anymore) for the same reason. Light intensity becomes reduced and possibly some color shift in the output spectrum. Of course our light are usually on for much longer periods of time than aquarium keepers but I'm also not sure of roughly when CFL's begin to lose their "new" characteristics...might be good for years, might not *shrugs*

I am a bulb collector (or was) and have collected and bought additional bulbs every year for 4 years. When I started a grow last September, I realized I did not know what were my old or oldest bulbs. Some were 3 years old, some were 2 years old, and some were one year old. So I bought a $110 light meter.
When I compared some 65, 85 and 105 watt bulbs, I saw that some bulbs were putting out twice as much as some others. I never understood the meter, or what it was measuring but some 105 watt bulbs were 6000 something and some were only 3000 something. I just gave away the old ones and will never use an old bulb again. I think they are like tanning bulbs and do wear out after a year.

 

[Lil Neutrino]

I hang on to all kinds of old stuff too...I've gotten better about throwing it out over the past few years though with all the moving I've done. Less there is the better!

Is it worth putting a reflector on CFL's? I recall reading in a few places a little while back that fluorescents are relatively poor at "throwing" light long distances. Reason being that the extra distance it travels from the bulb to the reflector and back to the bulb then to the plant was enough to reduce the reflected output at the plant to make it more trouble/cost than it was worth. On the other hand I see a lot of people using reflectors with CFL's...and a lot without. If you still have that light meter and a spare CFL sitting around maybe you could rig up something simple and run a few tests?

I need to get my chandelier constructed tonight or tomorrow and I've been debating whether or not to mess with a reflector other than to keep so much light from shining out the back of the exhaust vents. I'm pretty much flat broke atm so any unnecessary expenditures I'm holding off on for now.

 

[Setting Sun]

I've found that for 2700k purposes, the 23w CFL *floods* with the built-in reflector work very well.

Costco has them at 4 for around $10.

In fact, these focus the light so well, that you don't want to place them quite as close as regular spiral bulbs.

 

[OldMedUser]

I hang on to all kinds of old stuff too...I've gotten better about throwing it out over the past few years though with all the moving I've done. Less there is the better!

Is it worth putting a reflector on CFL's? I recall reading in a few places a little while back that fluorescents are relatively poor at "throwing" light long distances. Reason being that the extra distance it travels from the bulb to the reflector and back to the bulb then to the plant was enough to reduce the reflected output at the plant to make it more trouble/cost than it was worth. On the other hand I see a lot of people using reflectors with CFL's...and a lot without. If you still have that light meter and a spare CFL sitting around maybe you could rig up something simple and run a few tests?

I need to get my chandelier constructed tonight or tomorrow and I've been debating whether or not to mess with a reflector other than to keep so much light from shining out the back of the exhaust vents. I'm pretty much flat broke atm so any unnecessary expenditures I'm holding off on for now.

You could just use tin foil. It can lay right on the bulbs. The stuff made for barbeques is heavy duty. Dull side for reflector.

 

[MI-grower]

WOW guys thanks for posting all of this information, it was very helpful.. I am presently growing with cfl's so I got to say thank you Roseman for doing this journal and Thank you to everybody who has contrubited as well.... Mad props to you all!! Once I get through building my new light I'llbe sure to show it off here....lol

 

[Roseman]

I hang on to all kinds of old stuff too...I've gotten better about throwing it out over the past few years though with all the moving I've done. Less there is the better!

Is it worth putting a reflector on CFL's?

I guess so, I do it. I can see the reflected light and I just hate for any to escape by, so YES, I use and recommend the reflctors.


I recall reading in a few places a little while back that fluorescents are relatively poor at "throwing" light long distances. Reason being that the extra distance it travels from the bulb to the reflector and back to the bulb then to the plant was enough to reduce the reflected output at the plant to make it more trouble/cost than it was worth. On the other hand I see a lot of people using reflectors with CFL's...and a lot without. If you still have that light meter and a spare CFL sitting around maybe you could rig up something simple and run a few tests?

The major weakness of CFLs is they do not penetrate deep into the foilage. But, I can put mine two inches near, and am well pleased with the tight condensed buds I get. I did see if the Reflectors reflected the light, as well as the mylar, tin foil, flat white and glossy white paint and mirrors. And YES, the reflectors did better than the white panels and not as well as the mirrors, tin foil and mylar.

I need to get my chandelier constructed tonight or tomorrow and I've been debating whether or not to mess with a reflector other than to keep so much light from shining out the back of the exhaust vents. I'm pretty much flat broke atm so any unnecessary expenditures I'm holding off on for now.

Its pretty easy to make a DIY reflector, and I urge you to capture the escaped light, as little as it might be, it can still be captured and used. It will be interesting to see if anyone else responds, but almost all of the CFL growers I know either place the bulb down into the canopy, or use some kind of reflector.

 

[PhishyPhil]

CFL Light Tutorial

if you can get the reflectors shown in this pic ^^ i'd do it. stay away from the plastic ones as mentioned. the good ones can be purchased at any good hardware store for like $15, and its well worth it imo. good luck buddy~

 

[Setting Sun]

If you're using spiral CFL's in a horizontal position without a reflector, *50%* of your light is illuminating your ceiling instead of your plants.

If you're using them vertically *above* the canopy, you're doing even worse, as they don't radiate much at all along that axis.

The escaped light in those situations is huge.

 

[Roseman]

If you're using spiral CFL's in a horizontal position without a reflector, *50%* of your light is illuminating your ceiling instead of your plants.

If you're using them vertically *above* the canopy, you're doing even worse, as they don't radiate much at all along that axis.

The escaped light in those situations is huge.

You are so right!

 

[PhishyPhil]

indeed you two^^

furthermore, if you pay for the lights, and you pay for the elec. bill, you may as well take advantage of as much of your lighting as possible, because your paying for it anyway

 

[Roseman]

indeed you two^^

furthermore, if you pay for the lights, and you pay for the elec. bill, you may as well take advantage of as much of your lighting as possible, because your paying for it anyway

You are so right!

 

[Lil Neutrino]

Thanks Roseman...I guess early on I got the wrong information stuck in my head, I'll have to remedy that this time!

If you're using spiral CFL's in a horizontal position without a reflector, *50%* of your light is illuminating your ceiling instead of your plants.

If you're using them vertically *above* the canopy, you're doing even worse, as they don't radiate much at all along that axis.

The escaped light in those situations is huge.

Yeah, I had read about that...I've been trying to keep the lights in a cone shape over the top of the plant. Not really vertical but not horizontal either, I haven't doubted that it's not the most efficient method but have been debating how to do the "real" chandelier for weeks. Thought I had it figured out and then realized the hardware store didn't carry the sockets I wanted so that sent me back to the drawing board until I saw the one made out of PVC fittings here.

furthermore, if you pay for the lights, and you pay for the elec. bill, you may as well take advantage of as much of your lighting as possible, because your paying for it anyway

Good point lol. +rep for everyone if I can

 

[Lil Neutrino]

Another note of interest...efficiency. I dug around on HD, Lowe's, Ace, etc. and found that most bulbs found in popular hardware stores were mostly equivalent in lumen outputs given a specified wattage (all bulbs are 2700K models).

~ = approximately
68W ~ 4200L ~ $15 @ HD **61.7 L/W**
42W ~ 2600L ~ $10 @ HD **61.9 L/W**
26W ~ 1700L ~ $2.80 @ Ace when bought as a 10 pack **65.4 L/W**
23W ~ 1600L ~ Don't know, didn't really look since for three more watts you get 100L of additional output. **69.6 L/W**

Which bulb wattage is best? Depends on your grow and your budget. It will cost you more in bulbs to get the same lumen output from 68W as it does from a couple of 26W but the standard wattages increases by ~162% from 26W to 68W. Since it's not an integer multiple of the original wattage 2 26W is not equal to the next larger which is the 42W and so on.

Another thing to consider is the hardware costs required to rig up more lights. The question here is how long do the bulbs have to last with the rest of the chandelier hardware before you reach the break even cost point? You will need to know your cost per kw along with your planned lighting cycle for the entire grow to calculate this but it can be done. The point where the extra cost of the additional sockets and such is made up for by the extra efficiency/output of the lower wattage bulbs versus higher wattage bulbs with less required hardware but reduced lumen output.

2 26W CFL's (52W)= 3400L @ ~$6
or
1 42W CFL = 2600L @ $10

2 42W CFL's (84W) = 5200L @ $20
or
1 68W CFL = 4200L @ $15 (addition of a supplemental 23W or 26W will cost about the same as 2 42W's and increase the lumen output another 600-700L above what the pair of 42W's could do)

3 26W CFL's (78W) = 5100L @ ~$9
or
1 68W CFL = 4200L @ $15

As you can see from the above examples there is a definite advantage in going with multiple smaller wattage bulbs in regards to luminosity. However more bulbs means more mounting hardware.

1 1/4" T @ HD ~ $1.27
1 1/4" Elbow @ HD ~ $1.25
Rubber coated lamp socket @ HD ~ $3.27 (Rubber not required but it's all mine has)

I run 11-12 26W CFL's at the most right now which yielded some very sticky and rock hard buds during my first grow but also would require $30+ just in lamp sockets and another $20+ for the PVC. Now the question for me is, "Should I go with larger wattage bulbs and less hardware costs along with reduced light...or suck it up and stick with a bunch of smaller bulbs?"

When asking yourself that question it really boils down to your pocketbook. We all know that usually the more light the merrier and a mere $50-60 for a better yield may pay for itself in a grow or two...or maybe not. Unfortunately, sort of, I already have the bulbs and am still on a limited budged but the thought of paying $30 just for the sockets is hard to swallow atm lol. Too bad I can't return all the plug-in adaptors and Y-splitters I bought the first time around for a credit...

Anyway, I just wanted to point out an important difference in these bulbs regarding lumens per watt. Although even armed with this knowledge it does not become an easy decision as it boils down to a compromise between cost and yield...but then again we're used to that, right? One thing I am unsure of is the temperature differences between say two 26W bulbs and a single 42W bulb and so on. If anyone has any first-hand experience especially with temperature differences between them please post them!

 

[Setting Sun]

In my experience, multiple smaller bulbs run cooler than larger bulbs equaling the same wattage.

Specifically, four 23w bulbs ran around 2F cooler than two 42w bulbs.

 

[Blissed Out J]

Here is my new setup: 3 65wt at 2700k and 8 23wt at 6500k. I suppose I should buy 1 more bulb to make it an even 12. I will then hook up 6 bulbs into 2 outlet adapters. Below is an example. Let me know what you guys think!

 

[Roseman]

Another note of interest...efficiency. I dug around on HD, Lowe's, Ace, etc. and found that most bulbs found in popular hardware stores were mostly equivalent in lumen outputs given a specified wattage (all bulbs are 2700K models).

~ = approximately
68W ~ 4200L ~ $15 @ HD **61.7 L/W**
42W ~ 2600L ~ $10 @ HD **61.9 L/W**
26W ~ 1700L ~ $2.80 @ Ace when bought as a 10 pack **65.4 L/W**
23W ~ 1600L ~ Don't know, didn't really look since for three more watts you get 100L of additional output. **69.6 L/W**

Which bulb wattage is best? Depends on your grow and your budget. It will cost you more in bulbs to get the same lumen output from 68W as it does from a couple of 26W but the standard wattages increases by ~162% from 26W to 68W. Since it's not an integer multiple of the original wattage 2 26W is not equal to the next larger which is the 42W and so on.

Another thing to consider is the hardware costs required to rig up more lights. The question here is how long do the bulbs have to last with the rest of the chandelier hardware before you reach the break even cost point? You will need to know your cost per kw along with your planned lighting cycle for the entire grow to calculate this but it can be done. The point where the extra cost of the additional sockets and such is made up for by the extra efficiency/output of the lower wattage bulbs versus higher wattage bulbs with less required hardware but reduced lumen output.

2 26W CFL's (52W)= 3400L @ ~$6
or
1 42W CFL = 2600L @ $10

2 42W CFL's (84W) = 5200L @ $20
or
1 68W CFL = 4200L @ $15 (addition of a supplemental 23W or 26W will cost about the same as 2 42W's and increase the lumen output another 600-700L above what the pair of 42W's could do)

3 26W CFL's (78W) = 5100L @ ~$9
or
1 68W CFL = 4200L @ $15

As you can see from the above examples there is a definite advantage in going with multiple smaller wattage bulbs in regards to luminosity. However more bulbs means more mounting hardware.

1 1/4" T @ HD ~ $1.27
1 1/4" Elbow @ HD ~ $1.25
Rubber coated lamp socket @ HD ~ $3.27 (Rubber not required but it's all mine has)

I run 11-12 26W CFL's at the most right now which yielded some very sticky and rock hard buds during my first grow but also would require $30+ just in lamp sockets and another $20+ for the PVC. Now the question for me is, "Should I go with larger wattage bulbs and less hardware costs along with reduced light...or suck it up and stick with a bunch of smaller bulbs?"

When asking yourself that question it really boils down to your pocketbook. We all know that usually the more light the merrier and a mere $50-60 for a better yield may pay for itself in a grow or two...or maybe not. Unfortunately, sort of, I already have the bulbs and am still on a limited budged but the thought of paying $30 just for the sockets is hard to swallow atm lol. Too bad I can't return all the plug-in adaptors and Y-splitters I bought the first time around for a credit...

Anyway, I just wanted to point out an important difference in these bulbs regarding lumens per watt. Although even armed with this knowledge it does not become an easy decision as it boils down to a compromise between cost and yield...but then again we're used to that, right? One thing I am unsure of is the temperature differences between say two 26W bulbs and a single 42W bulb and so on. If anyone has any first-hand experience especially with temperature differences between them please post them!

There are lumens per watt, charts, and arguements for smaller wattage bulbs on the first page of this tutorial, along with more discussion on the above