conversion bulbs don't produce both spectrum's of light.i use the hortilux for veg because i run 600 watt hps and don't want to buy another ballast and bulb. these bulbs are for using your current system with out having to switch your ballast. so if you have a hps system bulb with a red spectrum you want to purchase the 600 hps conversion, or vise versa. when its time to switch to flowering you need to take out the bulb and run your hps system with the bulb it came with.