Distance of 1000w hps in 4x4 for optimum yield?

I have 16 plants which I vegged for 2 weeks in my 4x4 tent. I currently have my 1000w hps air cooled light about 18 inches above the canopy. Temps are about 77-79 while lights on. Is 18 inches a good distance in my situation? Should I move it closer? further? Any advice is appreciated as I am trying to get max yield out of this crop.

hold your hand at the top of the canopy for a minute,if it becomes uncomfortable, it is to close.

'I think 18"s ideal , the heat test on the hand is a good test. When you move over to the flowering stage you should be moving your lamp up every 2nd day, well thats my experience.

18" is good with a 1kw. I keep mine about 20" also in a 4x4 tent. I try and stay within 12-24" from the canopy with my 1k. Just make sure your not light bleeching your plants but where you are now you will be good. You could run into bleeching issues under 12", I did around 9" with a stationary 600w.