I don't go by the wattage, but more the light output. A 23w cfl puts out an equivalent light output of a 100w incandescent bulb. The watts per gallon rule is basically a dead rule. Get the 23w 6500k daylight cfls.
Most stem plants will do well. Ludwigia repens, rotala rotifundia, and anacharis/elodea are good fast growing stem plants. Don't expect growth to be super fast, mine grow at about an inch a week. Also this setup is great for anubias, crypts, and java ferns. Most swords will do well also and water sprite. S. repens has done well under these lights. I get decent growth and have transplanted cuttings to all my tanks from the 125g. I trim my stems maybe once every other month. It's a hobby so it works out great for me.
Oh that's cool. Well if the CFLs really are that bright for you and do a good job growing, then it sounds like a go. I read though, that most people who use cfls go by the actual wattage and not the incandescent equivalent (I.e. they wouldn't consider it to be 300w, but 69). In any case, I was either thinking of using those or some cheap 4 ft long shop lights. I have my 100g in an outdoor sun room, so it gets a bit of sunlight as well, so maybe I might not need as much intensity.
Any plants you can recommend for low/medium light, that can grow pretty fast?
I have a question about lighting. I read in a post that you have a 125g with just 3 23 watt CFLS in brooder lamps. I myself have a 100g and am looking for cheap but good lights to grow plants. My question is: You only have 69 watts total on your 125 gallon tank - that's barely more than 1/2 watts per gallon. How can you grow plants with such low lighting? Are you also growing plants that are considered 'high light' plants? (If you are indeed doing so, it's a message of hope for me, because I thought I would need much higher wattage)