Distance Between HPS Light and Plant????

anyone know a general distance that they've had success for with a 400w HPS bulb. i was thinking around 15-20 inches? is that too far? too close?

the ballast is for a 400w HPS/MH bulb so i'll be using both bulbs. are the distances the same for MH bulbs?

It depends on what setup ur using. Some ballasts get hotter than others, and may or may not be in the hood of the light itself, there's tons of factors. To answer ur ?, for best results, u want the plants as close to the light as u can get em WITHOUT BURNIN EM UP. Check the temps at different distances from ur light to avoid burnin em, or u can use the 'hand check technique"

richjames said:

or u can use the 'hand check technique"

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right there brotha.turn that light on and put ur hand at different distances to check the heat.. you can normally get em pretty close with a strong fan blowing.

not sure if this works but it seems like a good idea-take the temp about 12 inches away from the light.. then lower or raise depending on the heat. if ur under 75 u can prob move it closer. if ur over 80-82s than id move it farther.

thanks a lot guys. very informative! and quick too! i'm really starting to like this website!!!

lots of help here from lots of people