poppinsmokey
Well-Known Member
Started my 600 at 24", no burning and temps were managable w/ just oscillating fan. Moved light to 16" - 18" and radiant heat burned one plant with minor heat stress on others. My 4' x 2' x 7' area w/ unvented reflector is optimal at 20 - 22" average above canopy. I usually start it at 22" above, and raise it when plants grow within 19" - 20". Again this is an uncooled, 600 watt HPS with an oscillating fan blowing at canopy in a closet. I researched this thoroughly before using HPS. Most info you will find will put a 600W HPS 18" - 30" above the canopy.
Using the back of your hand, hold it directly under light at canopy level for 60 secs. If your hand stings, the light is too low. If it is just comfortably warm, you are very close to where you need to be.
Using the back of your hand, hold it directly under light at canopy level for 60 secs. If your hand stings, the light is too low. If it is just comfortably warm, you are very close to where you need to be.
