PAR is not accepted by all growers as being accurate (many think it's something that bulb manufacturers came up with). At any rate, in calculations I've made, the difference between PAR and lumen output is small, and PAR values are rarely given. And lumens are not given by watt; watts have nothing to do with light/ Watts are measures of energy; they say how much energy your light source uses. You can determine efficiency in terms of lumens per watt.

Which gets to the next point...One difference between CFL and HID lighting is that HID lighting is much more efficient. HPS usually produce a minimum of 100 lumens per watt; that's 40% better than CFLs, which are around 70 lumens per watt, regardless of size. But if you've got a small are, as others have noted, HID lights can cause as many problems as they create. If you're in an area of 3 sq. ft. or under, you may be better off with CFLs. You don't get as many heat or stress issues. But, yeah, once you go beyond that, HPS is always going to be more efficient...what people might call â??better.â?

As long as you're getting 5,000 lumens per sq. ft. and are pretty good about conserving the light you have (reflectors, reflective walls, etc.), you're going to get good results. And, sure, a small HPS and some CFLs will do very well.