In planted tanks I like using "daylight" type bulbs. You don't have to spend a fortune on them. Anything that says pet or aquarium and sold in the pet store will always cost more. I get my bulbs/tubes from Home Depot, Lowes or Wal-Mart. For your size Home Depot may be the place. Most sell GE or Phillips "Daylight Deluxe". The thing to look for is The "K" or Kelvin Rateing sometimes called color temperature. The ones found at non-pet stores will have a max of 6500K. They put out a blue/violet light. They really show off your plants and fish well. When the light hits the water the blue/violet makes everything look like mid-day, very bright. You can find the K-rating next to the Watts, Lumens, C.R.I. information on the bulb.

Thanks for the advice. I went out to the pet store and got the expensive ones. In 6 months Ill try the hardware stores. Thanks.
I modified my light fixture and put in an electric balast, I got it from home depot. It works great! It was $25, no need to pay $65 or better from a pet store. In doing that I added an extra bulb. So my 24" fixture now holds 3 x 18" bulbs. The balast was made to power either 3 or 4 bulbs. Its great. Id like to talk my sister in to letting me do her fixture so I can document and take pictures of the procedure. Its very simple. Anyway, when I went out and bought the expensive bulbs, I got one that is 50/50. Then about a week later my water started to get realy cloudy. I dont know if it was an algea bloom or a bacteria. When I shot H2O2 into the tank, I did not get any fizz so that makes me believe it was algea. (check out this link for H2O2 being used in aquariums, http://www.malawicichlidhomepage.com/aquainfo/algae_peroxide2.html, it works great if you use it in light) Any way, the question. I have heard that the 50/50 bulbs do not help plants in freshwater and they promote bad bacteria. Is this true?

Yesterday I emptied the tank and put in a new substrate. Before I had sand and gravel, the plants didnt seem to like it too much. So I got the Eco complet mixed with alittle Profile (shultz I think) then a layer of medium granit. So since I emptied the water, Ill never know what was growing. I took out the 50/50 bulb and went with a power glow. Anyway, thats my tank story.

Thanks.