doboyfresh
Active Member
Can anyone explain the main differences and how each make a difference. Also which matters more. CFL of course.
Actual Wattage VS. Lumens
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Gastanker
Well-Known Member
Wattage is a measurement of electricity. Lumen is a measurement of light. The higher the wattage (amount of electricity) the higher the lumen (amount of light).
You want more of both.
Higher wattage lights produce more lumen and throw that light farther - so a 23w bulb may throw 3" of usable light whereas a 45w will throw 6''. If you use 2 23w bulbs you increase lux but not lumen and thus there is twice as much energy at 3" but they still don't throw 6''.
You want more of both.
Higher wattage lights produce more lumen and throw that light farther - so a 23w bulb may throw 3" of usable light whereas a 45w will throw 6''. If you use 2 23w bulbs you increase lux but not lumen and thus there is twice as much energy at 3" but they still don't throw 6''.
lumens is a more direct measure of what the plant will use, it tells you how much light intensity you will have
most cfl's don't differ that much in efficiency, so actual watts is a useful measure, 50 watts per square foot is the typical minimum
to get pickier, some talk about PAR lumens, which takes into account the spectrum of the light, some parts of the spectrum are better for plants
lumens by itself is a measure that refers to the perceived brightness by the human eye, which is useful for the primary purpose of these light bulbs
hope that doesn't confuse things
most cfl's don't differ that much in efficiency, so actual watts is a useful measure, 50 watts per square foot is the typical minimum
to get pickier, some talk about PAR lumens, which takes into account the spectrum of the light, some parts of the spectrum are better for plants
lumens by itself is a measure that refers to the perceived brightness by the human eye, which is useful for the primary purpose of these light bulbs
hope that doesn't confuse things
jawbrodt
Well-Known Member
For most the lights we use for growing, "lumens" is the number that is most important(LEDs are one exception), and the number you should use, when deciding what to use. 3000 lumens per square foot, is the number that many accept as the minimum intensity that'll grow nice healthy(and bushy) plants, and seems to be pretty accurate. I use a light meter, and shoot for that number, myself, both with flouros and HPS. Also, keep in mind, that placement is everything, once you have the lights capable of providing 3000 LSF(lumens per square foot). For example, a 5000 lumen CFL will give your plants around 5000 lumens of intensity, if they are placed close enough.(an inch or so) If they are 5" away, your plants might only be getting 1500 lumens, and your plants will stretch. Light loses intensity very quickly, see "inverse square law" for more on that.
As for wattage....I've heard anything from 100 to 50, watts per square foot, is a good number to use, and it's not very useful, unless you get lucky, or know what intensity(lumens) is actually reaching your plants. IMO, using wattage, is mainly for HIDs, and calculating how much light will be needed to cover a given area. My advice for all of this....when in doubt, go bigger. You won't run into any problems with having too much light, unless you are well above 10,000 LSF, which doesn't happen often.
As for wattage....I've heard anything from 100 to 50, watts per square foot, is a good number to use, and it's not very useful, unless you get lucky, or know what intensity(lumens) is actually reaching your plants. IMO, using wattage, is mainly for HIDs, and calculating how much light will be needed to cover a given area. My advice for all of this....when in doubt, go bigger. You won't run into any problems with having too much light, unless you are well above 10,000 LSF, which doesn't happen often.