how far

[smoothe]

ive got a 400w hp and some seedlings witch are about 2 weeks old how far should light be with out hurting them did have floros but they burnt out so the onley light ive got is that 1 please help

smoothe Reviewed by smoothe on 05-10-2005. how far ive got a 400w hp and some seedlings witch are about 2 weeks old how far should light be with out hurting them did have floros but they burnt out so the onley light ive got is that 1 please help :confused: Rating: 5

[Zandor]

How close you can place the light is really determined by the temperature at the top of your plants. 12â?� or less is all the same lumens so itâ??s 12â?� to 48â?� we have control of and the closer to the 12â?� mark the better because it provides the most lumens to the plant. To close and you burn the tips to far away and you give up luminance penetration (PAR). Next is Luminance loss. Most experts are in agreement that light intensity diminishes exponentially fast.

For example:
A 400-watt MH from 0â?� to 12â?� is about the same luminance say 55000
Same light at 24â?� the luminance is now about 30000

Still good

Same light at 36â?� the luminance is now about 1200
Fan leafs block most of the light so nothing below sees enough of the light of day to do any good.

About 16â?� is average if your plants get too tall just bend them over (if you bend them over the buds get more light and grow bigger). You could crop them to keep them short and bushy you crop between the 4th & 5th node early in the vegetation state for best results.