roseman very informative post,
with all thats been discussed, i have a question to ask, maybe it was covered and i skimmed over it.
i am making a box 4'wx3'dx4't how many and what size cfl,s do i need? of course i am going to bloom my plants at 24" trying to keep them small
yep, you skimmed right over it. On the very first page where most of the info is, it says
How much light is needed for growing?
Depends on the size of plant you are trying to grow. I'll try to answer this "in general" instead of being specific to one size plant. Light seen and perceived with the human eye is measured in Lumens. There is an ideal amount of lumens for growing and a minimum amount of required lumens. The very minimum amount of light required for smaller sized plants grown is around 3000 lumens per square foot. Let me put emphasis on "minimum amount" of light. However, that's not 100% exactly 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 the reflectivity of the grow area. The ideal amount is somewhere around 7000-10,000 lumens per square foot for average sized plants. As long as the plants do not show burn, as much light can be used as you want to use. (Note, the sun produces about 10,000 lumens per square foot, on a sunny mid summer day).
Contracy to "talk" you CAN have too much light.)
Determining lumens for your grow area:
First determine the square footage of your area (example in a 4 foot by 4 foot area, there is 16 square feet, 2 by 2 feet is 4 Sq ft. ) If you have a 1000 Watt High Pressure Sodium Light Bulb, that produces approximately 107,000 lumens. Divide this by 16 (your square footage) 107,000 divided by 16 = 6687 lumens per square foot. So just divide the total amount of Lumens, by the total amount of square feet, and that's your lumens per square foot.
Many people have problems calculating the math.
You have a 3 X 4 and that = 12 square feet of grow space. The above says you need a minimum of at least 3000 lumens per sq ft, and a Maximum desired amount of 10,000. Half way would be 6000 or 7000 lumens per sq ft. 7000 is ideal. You 12 sq ft times 7000 lumens would be 84,000 lumens needed, on average, half way between the 10,000 max and 3000 mimimum.
You can look at the chart on page one and see that most CFLs provide 60 or 70 lumens per watt. We'll go with 70 lumens per watt.
84,000 lumens needed, divided by 70 per watt= you need 1200 watts to be "ideal" and half way between Minimum amount needed and the Maximum amount. If you go with 42 watt bulbs, you need 28 bulbs. If you go with 105 watt bulbs, you need 11 bulbs. and again, that is for the ideal amount. Most of us use less than perfect and get by.
If you went with bare minimum light, say 3000 lumens per sq ft, you'd need 36,000 lumens, divided by 70 = 514 watts, or about 12 42 watt bulbs at very bare minimum needed.
Post # 117 says:
I saw a dude, a young college student on limited funds grow a plant in his closet with ONE 42 watt 2700 K bulb. He was so proud and got a little over a half ounce of dried bud from his plant.
I have seen many many growers use one bulb only, or two bulbs or just three bulbs and have all one kelvin, or all 6500K and no 2700K, or be 26 watt bulbs, and just did not have the dual spectrum. BUT, they got a harvest and were very grateful and proud to get it. I did my first grow with only two 65 watt bulbs in VEG and added two more in Flowering. I was so very proud of that grow too! Mostly I was proud I did not kill them and they lived.!!
You just have to go with what you got, or can get, sometimes!
After a little game of find the broken connection, it ended up being just a lose wire nut! 
Very informative. 
