400 HPS Distance

Is it the heat or the intensity!?!?!?

What is the proper distance from my 400 HPS to my plant's leaves? I have zero heat issues - I can put the back of my hand on my light's glass and hold it there forever, it just feels nice and warm. The hood is air cooled and I run a massive amount of air through there.

So do the rules of 1'-2' still apply? Or can I slowly work my light right down to the canopy?

Thanks for the opinions everyone.

i have mine at about 8" and its been fine for 2 grows. if you notice leaves turning color after a day or curling or hairs on bud discoloring move it up

It's the heat that gets to your plants. With the hood being air cooled and using only 1-400w light, you can have your light a lot closer than 2 feet. Start at 1 foot and slowly work your light down. I went to my flowering room with the 2-400w lights and they are about the same as Overfiend, just about 9 inches away from the tops.


Widow

Thanks guys! The lamp is on the way down and I'm watching for trouble.

mine is totally uncovered and is a foot away with no problems. i just have a small fan

I have my 400 hps like 6 inches away but I have airking fans.

JonnyDankness said:

I have my 400 hps like 6 inches away but I have airking fans.

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Do you have the fans blowing directly on the hood/bulb?