with adequate air flow you should be able to have the ligh between 25-40 cm from your plant.. place a fan blowing on the area between your light and the top of your plant... have it at a slght angle so that it is blowing upward....

every 30cm the light looses half of its effefective lumens/growing power... this is why it I so important to keep the light close to the tops of your plants... using a 1000 watt hps bulb, every plant within 25cm inches will/should produce a main cola of 20-30 grams...

I have repeated this over and over yet few take this advice... even though I posted pictures of a cfl grow with a 15 gram cola...

iloveyou..

FANs.. many many fans.. are key..

iloveyou