400 watt HPS Distance From Plants

ive got a 400 watt hps cooltube with inline can fan attached. how far away can i keep the lights from that plants?

Your hand can tell you the EXACT distance to keep the light. Just put your hand under the light (leave it there for about 60 seconds) and when it gets too hot for your skin... its too hot for your plants.

if thats the case i can put it almost touching the cooltube

yea i got a 600w cooltube as well and its roughly 5 inches from my plants. just be careful when you first switch to flower as they will grow real fast towards that light and you don't want to burn them

i have a 400watt hps in a small space with a inline fan and no cool tube vertically and about 2 inches is the limit. this is no cool tube btw