light distence

ok i have a 600w hps with reflector, its not a cool hood but my question is how for away from the plants should i have this

With all lights you need to realize if you can't take the heat either can the plant. LED's and Flore. can be an inch or 2 away from a plant because of the lack of heat. An Hps puts out alot of heat so simply turn it on put your hand under it and what ever distance your hand can take the heat is the distance your plant can take. about 2 feet or so.

neerer than about 18 inches tends to burn my plants, the bigger the bulb the father the effective lumens reach, so you dont need to be too close to a 600 or 1000 as you would a 400.