What is the major difference between the Metal Halide and High Pressure Sodium lights? Why would you prefer one over the other? I have read some things about mixing up the lights for different time periods, but I can't seem to find out why. Also, at what times would you switch off between the two?
Most people use MH for veg (light on 18 hours off 6 hours) and then switch to HPS when they start to flower (light on 12 hours off 12 hours). You can also use fluorescent lighting during veg if you are worried about your electric bill. Each light gives off a different light spectrum. I believe, and anyone correct me if I'm wrong, that MH gives off more of a blue spectum while HPS gives off a red spectum. Do some research on the forum dude. Most of this stuff is covered. Go to the search bar and type in what you are looking for.