I believe in the HPS over CFL's by about 300%. I started out using CFL's exclusively, In time I learned that not only do HPS have better Lumen per Watt which means less heat per watt, They also have a much higher PAR which is a measure of how much light is actually used by the chlorophyll. PAR stands for Photosynthetic Active Radiation. Science talk for "plants only use red and blue not green".
A CFL bulb is coated with 3(usually) coats of phosphor, 1-red 1-green 1-blue to make white. They use different exact color phosphor depending on the desired kelvin(color temp) output. But even though it sounds great, in actual spectrum terms it sucks.
The HPS on the other hand uses actual spark. This "Spark" more closely simulates the spectrum of the sun. The sun gives off all light colors intensely(instead of just 3 for CFL),
This leads to More PAR.
Just look up all the terms that I've used and you'll understand completely.
CFL's are a waste of money, electricity and time.
HPS = More PAR per watt/less heat per watt
Zcomp Reviewed by Zcomp on . CFL vs. HPS I'm currently planning my grow, which will be in an attic. It's not my house so I can't exactly start drilling holes everywhere, but I think regardless it's a little drafty so it may ventilate itself! Haha. There is a window which I could use though. But my question is: CFL bulbs REALLY are attractive because of how low their watt usage is - but can you really go the whole grow with CFL bulbs? I would like some tips on this, as well as the pros and cons. If an HPS is just simply better, then Rating: 5