you need lumen output thats all your looking for. efficency isnt a must. a 400wtt hps is about 30,000 lumens maybe more. to achieve that would be about 10cfls. no math is needed u want as many lumens the correct spectrum and that is all. Take into account heat, and bulb life isnt a big deal when u see results.
JackdaWack Reviewed by JackdaWack on . HID vs CFL in a small one plant situation, given light spectrums being ballanced between each situation and all other factors the same, would you see a difference between ~300 watts of CFL, and ~150 watts of CFL supplimented by say a small 50 or 75 watt HID? my main areas of concern are with potency, density, and mass, as well as time till maturation. Rating: 5