Kelly,
a 24" fluorscent is always gonna ge 20watts. The only way to increase it is to change out the hood ballast to an electronic one, and overdrive the bulb to around 30-35watts..which still isn't squat.
I have a 29, and I had to spend about $100 to equip it with 110watts of power compact fluorescent bulbs.
You currently have under 1 watt per gallon, so your Hagen CO2 unit is kinda pointless...the plants arent' growing fast enough to really require extra CO2. once you hit 2watts per gallon, CO2 is a good idea, and after 2.5watts its mandatory, unless you like stringy plants covered in algae
YOu should be able to pickup a Coralife 30inch power compact fixture for under $100 online, which should have at least 1 65watt bulb in it. Try
www.hellolights.com for that. Otherwise hit
www.ahsupply.com and get a retrofit kit, and you can convert your current light to power compact for about $40