I made a light-bench using 3, T8 fixtures. Each one has two, 4-ft bulbs. (I use three, 2700k, and three, 6400 bulbs). I have used these for about a year. 6 bulbs X 2750 lumens = 16,500 lumens. (btw, the operating cost for 6, 4ft tubes is about $8.00 a month running at 15 hours a day)
A couple of months ago, I found a several light fixtures at a thrift store. These chrome fixtures were designed for use in bathroom, around a mirror. These 4 foot, 8 bulb fixtures are the small length as the T8 fluorescent fixtures. I paid $3 dollars. The thrift store I bought it from had 5 or 6 more or them. I did have to purchase some electrical cord and a plug and wire them myself.
I installed, eight, 26 watt spiral compact fluorescent 6400 bulbs. Each bulb produces 1750 lumens. 8 X 1750 = 14,000 lumens (almost doubling my lightbench lumen output)
I've been doing some experimenting. These fixtures are on separate timers. The T8's are on for 15 hours a day. The bank of compact fluorescents come on, in the middle of that 15 hour period for 6 hours.
When I put this together, the plants told me that using the tubes and the CFL's simultaneously were too much. The leaves started turning a very pale yellow, which is the plants response to TOO MUCH LIGHT. I had 2 options, increase the distance from the lights (which I did by about 6 inches) or reduce lumen output (which I also did)
When T5 VHO fixtures and bulbs are more in-line with my budget, I will most likely convert. Either that or LED.
But, keep this in mind. The "T" bulbs are measured in 1/8 of an inch. So T8 are 8/8 or 1 inch in diameter. T12 are 12/8's or 1 1/2 inch. The new T5's are 5/8 inch in diameter.
Did you know that spiral CFL (household lightbulbs) are actually T5's. I tested this myself with a caliper.
A good resource for more information on lighting is GardenWeb. They have a forum called "
Growing Under Lights", with some knowledgeable people who willing share alot of information.