Yes, I want to get technical here because what you are saying could be misconstrued or even be misleading. Lumens are the simplest, most readily available measure of light power. Lux simply refers to the amount of lumens striking a specific space...one lux = one lumen per square meter. (Since one square meter is almost exactly 10 sq. ft., you want 50,000 lux.) Anyway, it's much, much easier for growers to use information easily accessible. People can use a tape measure to see how big their grow area is. And easily available information, in the case of grow bulbs, is lumens.

Watts, on the other hand, have nothing to do with light whatsoever. It does not matter how easy they are to understand, they are completely irrelevant to light. They are a measure of the amount of energy a light source uses to produce light. Since there is a wide variance in efficiency between different light sources, watts are a very, very poor way of judging efficiency of lights for grow purposes. For instance--

150w HPS lightâ??15,800 lumens; 105.3 lumens per watt
1000w HPS lightâ??147,000 lumens; 147 lumens per watt
26w CFL lightâ??1750 lumens; 67.3 lumens per watt
4 lamp 4' T5 216w Fluorescentâ??20,000 lumens; 92.6 lumens per watt
100w of incandescent lightâ??1500 lumens; 15 lumens per watt

So, a 1000w HPS is over 40% more efficient than a 150w HPS...which is 50% more efficient than a CFL. In other words, you would need over twice as many watts of CFLs to do the job of a 1000w HPS. You'd need 50% more watts of CFLs to equal the light output of a 150w HPS. But a T5 fluorescent is closer to a 150 or 250w HID light. So there's not only variance in light output efficiency per watt between different types of lights, there is variance within the same type of lights. It adds up to a simple conclusions. Watts are not a good way of judging how much light you are producing.

For a 10 sq. ft. grow area, you would need:

One 400w HPS (50,000) lumens = 400w
Three 150w HPS lights plus 1 26w CFL = 476w
Two 4 lamp 4' T5 216w Fluorescent rigs, plus one 2 lamp 4' T5 108w Fluorescent = 524w
28.5 26w CFLs = 743w

Those substantial differences make the point. Use lumens per sq. ft. Try to get 5,000 per sq. ft. Maximize the light you create with reflectors and good reflective surfaces. With CFLs, that means about 70w to 75w per sq. ft. With HID lighting, the amount is at least 40% lower...even lower as you get into larger HPS or MH bulbs.
Roughrider Reviewed by Roughrider on . 3 weeks, 1x60watts cfl, opinions pls! Here we go, my first plant http://img507.imageshack.us/img507/188/imagen1473qx2.jpg http://img523.imageshack.us/img523/6948/imagen1474zh3.jpg http://img172.imageshack.us/img172/2008/imagen1475yn6.jpg http://img214.imageshack.us/img214/6114/imagen1476vx3.jpg Rating: 5