PFO 400W DE HQI Pendant & 20K Bulb - available at J&

[Quagmire]

And the last article shows 250w DE aren't much better than 250w SE.The best results come from matching bulbs to balasts for the best output.One thing to remember,unless I missed it,is that these test didn't use reflectors.So its possible with the HQI bulb,that you will get more light reflected back into the tank.