Be careful while *A* T5 bulb might have less power than a MH bulb, MH bulbs can hold their own vs T5s as far as efficiency.
	
	Here's an AA article that has a particular MH bulb, as well as a T5 fixture and a couple of the LED fixtures out there
	http://www.advancedaquarist.com/2010/2/aafeature2
	
	In particular 1 250w MH bulb (~300W output)  [images are a little too big to post]
	http://www.advancedaquarist.com/2010/2/aafeature2_album/figure_1_lumen_max_ushio_250w_14k_de.jpg
	
	vs a 6x39W ATi T5 setup,  ~250W output
	http://www.advancedaquarist.com/2010/2/aafeature2_album/figure_2_ati_t5.jpg
	
	It might be hard to tell by the charts, but the T5s peak at about 200, where as the MH are almost 300, that's 50% more light peak light for 20% more power.   Plus they both have fairly similar coverages (i.e. the halide isn't all at one small spot.  It should also be worth noting that this is a 14000K MH vs 6500K t5s, so the T5s should have that as an added advantage as well.