400mh how close?

[john appleseed]

anyone?how close to the tops of the girls? bare bulb in a 2x7x9 closet.1 exhaust fan and 2 inlet vents.there is a ac vent in there also but i keep it closed bcause of the exhost fan.so if zandor or mellow are 'round help a brother out please.

[0mn1v3il]

I've got the same setup with 2 400w mh and i keep the plants about 10-16 inches away. that seems to do the trick for me. temps are at 75-85

[john appleseed]

thanks dude i will be lowering the light now.

[HARDDON]

You can get your HPS or MH bulbs very close to the plants IF you have a fan blowing the heat off the bulb.

I have a 250W MH bulb that I can hold in my hand because of an intense fan I have blowing the heat off the surface. The MH bulb is now 5 inches from the garden canopy.

The plants NEVER feel it and respond quite nicely to closer MH light.

[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 36â?� 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. 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.

[HARDDON]

ok then....

moving my MH back to 12"

:)