Here's an excerpt from a post I made in my journal today that might help...
"Lighting tip from a n00b: Don't waste your money buying big CFLs. Their efficiency drops exponentially and even with a reflector you're going to lose most of the light that isn't facing the plant. There's also significant variance between brands. Do the math when shopping for bulbs. The way to figure this out is by dividing the bulb's wattage into its lumen rating to get the
lumens per watt.
Check it out:
250W 11050 Lumens, 4,000hr life, $39.75 per bulb
http://www.amazon.com/Apollo-Horticu.../dp/B00HG1J2PK
65W 3900 Lumens, 6,000hr life, $17.40 per bulb
http://www.lowes.com/pd_46931-75774-...ductId=3197521
23W 1640 Lumens, 12,000hr life, $3.50 per bulb
http://www.lowes.com/pd_302275-3-269...ductId=3201759
So we take 11050/250=44 lumens per watt, 3900/65=60 lumens per watt, and 1640/23=71 lumens per watt. That's a huge difference in efficiency, and we won't even get into cost savings

Watt for watt, the 23w bulbs would give you over 4600 lumens vs the big guy's 3900, and 17825 vs the big guy's 11050. Don't forget to knock off a good 30-40% to account for efficiency loss when figuring the total lumens that you want to hit the plant."