Optimum distance on the height of the lamps. Please help.

[absolutionbg 2]

Hello, My plants are second day flowering now and I was wondering what is the optimum distance on the height of the lamps.
My lamps are 2x600 HPS.

Thank you.

[Ganja XL 105]

I always used the ideal measuredevice, my arm, just measure the distance from your elbow to the top of your fingers, always feel how warm the plants tops have it ..more or less.

Thats the way i always did it and you always have your arm with you !

[Tokage 2,156]

I guess the closest you should have a 600w is 20cm away from the canopy and furthest around 80cm.
However, 20cm is very close and you will prob burn the top of the plant without proper ventilation. 20cm will also reduce the light spread and only partly be of use for the whole plant/s
Usually the use of an cooltube would be implemented at this close range.

Put your hand under the lamp right over the top of the plant, if the hand feels hot you have them to close, the hand should feel warm but not burning.
One 600w should light spread and area of 1x1meter up to 1,2x1,2 meter.