I'm no expert on the subject, but have done a fair amount of reading. The big deal with T5's has more to do with the reflector than the bulb. Because it is a single bulb, unlike a PC
, you can use a parabolic reflector to increase the amount of light hitting the tank instead of being wasted in other directions. I understand that the W shape reflector is nearly as good. If the Extreme is truly rounded around each bulb it may approach the parabolic shaped reflector for efficiency. But that's just a guess on my part. I would ask Nova if they have any data to back up their claim. I would love to see the PAR outpu between the Nova Extreme and the regular Nova with the same bulbs over the same tank. They should have that data.