don't waste your money on the first link!

yes there are big differences in bulbs....generic MH/HPS are not horticultural lights..they mayt hit some of the spectrums but are not designed or manufactured for growing...look at Hortilux or any well known brand of grow bulbs....if you go to your local hydroponics store they can help steer you in the right direction!:thumbsup:
stra8outtaWeed Reviewed by stra8outtaWeed on . Lighting Options I have a 400w MH and a 150w HPS and that's what I've been using to grow my first crop of four plants. I am trying to learn as much as I can about this stuff though because I'm trying to get my mom to grow pot (they can do it legally because she lives in Oregon and my sister has MS). I want her to start growing it so my sister quits spending so much money on it (she's a huge pot head), but more importantly so that they can sell some of it to make extra money (which obviously isn't legal). Rating: 5