Less light lower or more higher?

[fyouston]

Hey

ATM i got 2x400watt HPS lights in a smallish tent, i can either have one light on at about 30cm or both on with one at about 40cm and one at about 60-70cm to create an air gap in between as the temp gets too high if i do it any other way, i was wondering if the latter is going to have better results or if im better just using one and saving power.

[cptcannabis]

The easy way to answer this question is to get yourself a cheap light meter and measure the foot-candles (Fc) underneath both set-ups. You can probably find a light chart on the web somewhere too, that will tell you distance v. Fc, so you can have an optimal set up. I find with HPS, MH, and HID lighting, you typically want it no closer than 18" or so otherwise the plants will burn from the heat.

If temp is a problem with your two lights, I would personally opt for just the one in order to have a stable temperature. With the two lights, you would get more growth due to addl. Fcs, but you lose that extra growth with the heat going above 85F.