stoneslacker
Well-Known Member
With a fan blowing between the bulb and canopy I have my 250w 4-7 inches from my canopy. Thats with avg air temps 93+ in my grow box. I know people say to take temp at the canopy but I find cannabis can handle much higher radiant heat from the bulbs so my gauge is at canopy height shaded from the direct light. Just have lots of ventilation and air movement and push the limits of how close you can get.I switched from a 4ft 4bulb, much better for me. I switched early tho so they were only a few weeks old, but much easier to deal with space, and its actually cooler being I have much more room for airflow.
Dont have to worry about only having 3" of effective light, also if you have good airflow and cooling they can get pretty close to a 250W bulb, mine have been as close as 4" at times without burning.