Quote Originally Posted by irydyum
And the Darwin award of the week goes to you my friend. I invite you to come touch my HPS's and tell me how hot they aren't.

The real answer is you have to play with it a little. Some people won't let their plants come within 12" some 16". Like Horseman said, don't let it get much over 84 degrees at the canopy or you will probably have some heat stress issues. With my current setup i'm in the 6" to 8" neighborhood, no pun intended. Obviously if you have an open reflector or an air cooled one it will also make a difference. 12" to 18" should be a decent safe zone for a relatively mature plant, seedlings should be stay about double that distance away. Let us know what you end up with:thumbsup:
Going with some auto flowers (AK 47, Hindo Kush) this grow and wanted to try out HPS light to see how yield vs. my LED's. Also got a couple of Super Lemon Haze going for mother plants. Will see how it goes and I will play around with heat/temp and get used to HPS light. Got a fan going as well as exhaust fan, so far grow tent is at 76 degrees