1000w HPS distance

[trichrome]

How close should I be able to put my air-cooled 1000w to the canopy.
Had it running 16" but plants were drooping, moved it to 24" and plants are looking happy and reaching for the light. Im concerned about yield loss from the light being too far away.

 

[medmaker420]

mainly if its too hot for your hand to be there then move it back a bit

I would also do as you did, check for heat stress and drooping and play around with it a bit until you find the right spot.

Its a light intensity versus heat deal and each setup is different.

I would move it closer than 24" personally, light intensity drops FAST as the light gets further away.

There is a great graph somewhere that shows the lumen strength based on the light (400.600.1k) and inches.

That should be a guide BUT if they are stressin scoot it back like you did until you find the best spot.

Another thing, if it is heat, get a fan on the canopy which should allow the light to get closer.

 

[trichrome]

I don't think heat is a problem. The temps never go above 80 at the canopy. I have and oscillating fan between canopy and the lights.

 

[Mr. Greengenes]

I personally think yield gets a bit larger when the plants are a bit further away. Not sure exactly why but some ideas might include; Greater distance encourages growth of larger fan leaves (like a plant in partial shade outdoors) which translates to more carbohydrate storage and bigger buds. Or, it could be the less damaging effects of the radiant heat from the bulb.

I've done some outdoor growing in the Southwest desert areas. Hot dry desert canyons with intense sun and moving air produce plants with smaller, leathery leaves. I've also toured many local growrooms and noticed that beginners often put lights too close. In fact, moving the lights away is one of my most common suggestions. When someone has been growing with the lights too close for some time, the plants take on a look somewhat like the outdoor, desert/canyon plants. I prefer the lush growth and large leaves of the semi shaded plant and try to emulate that amount of light indoors.