400W hps.. How far away ?

How far away from tops of plants should a 400 W hps NON cool tube be???

put your hand at the level of the plants and if u can feel enough heat 2 burn the plants then u r 2 close. a gentle heat is fine.

ok I was wondering if anyone had an estimate

It's deffernt for everyone. Put it at 2 foot and work your way down untill you can get as close as possible to the plant without burning them.

..15 inches worked for me...with A/C air blowing between plants and lights. 400HPS Hortilux.

thanks guys!

12 inches is nice, but try to be no more than 20 inches, if you get any further you loos so many lumens that your 400w turns into a 250w light.
Adieu

copy that. Thanks all. I raised it today to about 14.5 inches. Should work.