You may be interested in reading the article by Mike Kirda in this month's Advanced Aquarist:
http://www.advancedaquarist.com/issu...03/feature.htm
He shows some PAR readings from a LED-lit tank that was showcased at IMAC this past year. The tank uses 3 LED bulbs totalling 13 watts, with PAR readings of 235 mE/m2 above water, 160 immediately below water, and 24 mE/m2 on the bottom of the nano tank it was used on. This tells me two things - one, LEDs are pretty bright, PAR wise, but they seem to lack the punch that other types of lighting have, like MH. The tank featuring 2 x 400W Ushio bulbs with 3 x 110W VHO actinics has PAR readings of over 400 just below the water surface, and drops to the mid-200's near the bottom of the tank.