optimal light height

emmpey · Dec 1, 2008

hello everybody,

i'm still tuning my grow in using an air-cooled 400w hps in a 1m W x 60cm D x 1.5m H cab.

i grow 24 clones (12 in every 4 weeks) spear style in pots which reach a finishing height of about 22 inches when done.

i have been keeping the light 8 inches from the tops, but i have noticed that the plants directly under the light look bleached out after a couple of days so i have raised the light to 12 inches.

is this high enough or should i go a bit higher? bearing in mind that 400w should be good for 1m square and i'm using 0.6m square. I want to get the best spread of light accross all plants wihtout losing too much from the lower buds.

thanks. :weed:

Boneman · Dec 1, 2008

What you need to do is the back of your hand test. Adjust your light and put your hand at the tops of your plants. If its not too warm on the back of your hand then your plants should be fine. With a 400w its recommended to be 14" away (or something close to that). 8" might just be a bit too close

emmpey · Dec 1, 2008

thanks for quick response! its a sealed air-cooled hood so i can keep my hand right under the light. being an ex CFL grower i'm used to keeping lights as close as possible, now I want to get best possible light spread for my space. I'll see how 12 inches is for now. good to know i can go higher though.

Bangers999 · Dec 1, 2008

emmpey said:
hello everybody,

i'm still tuning my grow in using an air-cooled 400w hps in a 1m W x 60cm D x 1.5m H cab.

i grow 24 clones (12 in every 4 weeks) spear style in pots which reach a finishing height of about 22 inches when done.

i have been keeping the light 8 inches from the tops, but i have noticed that the plants directly under the light look bleached out after a couple of days so i have raised the light to 12 inches.

is this high enough or should i go a bit higher? bearing in mind that 400w should be good for 1m square and i'm using 0.6m square. I want to get the best spread of light accross all plants wihtout losing too much from the lower buds.

thanks.

1.4mtr dude mind they are just babies

optimal light height

emmpey

Active Member

Boneman

Well-Known Member

emmpey

Active Member

Bangers999

New Member

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