The standard Cool White and Warm White work better than the
high-priced "Gro-Lux" or similar types. Probably the best
fluorescent lights are the 4-tube, T-5 high output. They
are also available in 2 and 8 tube; either 2' or 4' in
length, with a choice of 6.5K (blue) or 3K (red).

The 4-tube 4' would cover about 4 sq ft, one foot in height.
However the cost is almost as much as a 400w Ceramic Metal
Halide, which at about twice the watts and twice the
efficiency would grow about 4 times the yield. With a
good reflector, approximately 3' x 5' area is covered,
up to about 2.5' in height.

The CMH has more red than an HPS, and more blue than a
old-style MH; with a reasonable volume of output. It is
full-spectrum and can be used for all stages.

I use high output t8 lamps. i order them online from businesslights.com and they're actually quite cheap, since t8 is very highly mass produced for commerce. buy the 4100K lamp, it's a good balance of blue and red, should keep your plants stocky enough. also, i use double sided carpet tape, and cut mylar to fit the reflectors, this will increase the output of your fixture. mylar also comes online from businesslights.com or plantlightinghydroponics.com (same company). check to make sure the ballast in your fixture
actually produces enough current to fully drive the lamp. you may wish to buy a 40 watt electronic ballast from ebay designed for t12 lamps, and retrofit it; this would slightly overdrive the lamps to make them even brighter. What I'm saying is put a 40 watt ballast in your fixture and drive 32 watt t8 lamps with it, but make sure the ballast will really supply 40 watts worth of current before you buy it. if you're adventurous, you may wish to overdrive your fixture even more, but i suspect you will be quite happy with the results from this fairly simple modification, because you should find each t8 lamp is now burning brighter and putting out about 4,000 lumens, which will keep your plants very happy. Also be sure to keep the lamp within an inch or two from the top of the plants. Sativa.

Oh, and don't worry about the term "overdriving". the t5 lamps that growing shops recommend come with "overdriving" standard. you can easily run a 32 watt t8 at 40 watts (or even 54 watts) with absolutely no danger or hazard to anyone whatsoever. it's just utility company standards that keep mandating for lower and lower wattage, to save the strain on the electrical grid. for growers, we look for ways of increasing the wattage, because more photons = more plant growth. In fact my own setup is with a bank of 11 x 2-lamp shoplight fixtures, all t8 lamps overdriven to run at 54 watts. the lamps get a little bit more warm than running at 32 watts, but the ballasts all stay nice and cool, and the light output is quite a joy to behold. Sativa.

Well I am a pig. I use the typical MH or HPS lamps. I got two 1K lamps in a 10x10 room. Raises my elec bill by $100 per month. Seriously.

I like the lights because my plants grow like no others. I have folks that tell me I should not mix MH with HPS lights, but my plants tell me different.

If you want awesome indoor plants, buy a 1KW light and pay the electric bill. If you can, supliment the light with real light from the sun, its free.

BTW, I do not work for a power company, as stated I am a pig.

2000 watts per 100 square feet is only 20 watts per square foot. you're no pig. I'm the pig: I run 1200 watts/15 square feet 400Hps x 2 + 400 MH in a 3 x 5' growing closet = 80 watts per square foot. No, I'm the pig, I use a 35 cfm fan to exhaust the heat out of the room, and my cannabis plantation is VERY LUSH, and the yield is VERY HEAVY, and VERY POTENT :) Yeah, I pay a little for the electric, but I save money of having to buy my pot. I grow about $20,000 worth of pot per year. And no, pot is not a gateway drug, if you have good pot that's all you need. I have absolutely no desire for any other drug of any kind. Sativa.

Cannabisgrower - You make me laugh. That's some funny stuff. Thanks for your thoughts.

EG

cannabisgrower,

What I'm saying is put a 40 watt ballast in your fixture and drive 32 watt t8 lamps with it.

**************************************

Would a 40 watt lamp be brighter and more productive?

Do you change your lamps annually?

John

2000w per 10' x 10' area is about right. However you have only two points of light. I recommend instead, 4 or 5 of 400w CMH lights. With four such lights, you save 400 watts and yet the yield would be about 20% higher. That is for two reasons:

1. the CMH spectrum is about 85CRI, which means full spectrum
2. the CMH spectrum is not as spiky, and more continuous, than old-style MH.
3. having multiple points of light means mutliple angles of light, resulting in fewer shadows and better distribution of light.

Using a 40 watt ballast for a 32 watt tube, overdrives the tube to 40 watts, and results in very much more bright output. especially is you buy a TCP XHL lamp, which cost about $2.70
this is a very nice long life lamp, and I do not change my lamps annually. Modern T8 lamps have exceptional lumen stability, and only need to be changed every 5 years. Which is more reason to pay slightly more for the XHL TCP lamp.