If you're willing to build the fixture yourself, it's hard to beat LED
. Check out the LED
link in my signature to see my high-light planted tank using LEDs.
Here's my list of reasons to go LED
1. Energy savings - I'm using 30W of LEDs on my 20H. I'd have to use two or three times the wattage if I was using T5HO lights to achieve the same results.
2. No bulb replacement - LEDs last much longer than T5HO bulbs. My LEDs are rated for to put out at least 70% of their original output for 50,000 hours.
3. Flexibility - LEDs are small and don't require reflectors, so you can creatively pack a lot of light into tight spaces. You can also pull off cool sunrise/sunset effects if you're good with microcontrollers.
4. Spectral output - Plants like red and blue light. LEDs don't put out much light in the yellow-green spectrum that algae likes and plants don't.