help-250W CMH, how high above seedlings should reflector be?

[vindiesel]

??? i can place my hand with a few inches under reflector, and hand only feels warm, not hot. how high above seedlings should a 250 CMH be? i'm thinking like 6-8"...thanks.
vin

 

[FreezerBoy]

Wouldn't you know I find out my plant prefers low light AFTER I get my 250 CMH ... anyway, before I knew that I kept the hood as low as possible. Maybe 2" off the canopy.

 

[vindiesel]

so youur saying put it 2" or so off top of pot? right now i have it 7".

 

[Betty's Boy]

Maybe 2" off the canopy......canopy is the top of the plant's.....

 

[vindiesel]

i dont have a canopy yet. just planted sprouted seeds today. i lowered it to 4" above top of pot/soil.

 

[greenisgold]

Do not put it so low or you will cook the soil/seeds. Make sure the top of the soil is always moist, but not wet. Raise it back to a foot until they sprout. Once sprouted then move it down a few inches everyday making sure that the light is not to high so the seedling stretches to much.
Peace

 

[FreezerBoy]

i dont have a canopy yet.

The canopy is the top of your plant(s) If you have a plant, you have a canopy.

While there were heat issues with HPS, the CMH is pretty cool. The sun doesn't tailor it's power for seedlings, nor does the atmosphere provide humidity zones around individual plants. You'll lose half your light in the first 6" and the plant can tell. It'll stretch out to get to the stronger light. Your bulb is already recessed in the hood by about 4". You don't need much more between hood and canopy.

If you're too scared to start that low, s'cool. But, get the lights down asap. It's a weed, not a hot house flower.

 

[Doug_Marsh]

Where did you guys purchase your chm? Are they to big to fit in a bake-a-round tube like the mh? How many more lumens are they compaired to a regular 250hps? Thanks for the info

 

[FreezerBoy]

http://advancedtechlighting.com/cdmed18.htm

http://www.businesslights.com/hps-ballast-kits-c-190.html

Note bulbs are orientation specific. They'll work in the wrong direction but at the cost of lower life span. The 250 will fit a bake a round. HPS has slightly more lumens but, lumens are a measurement of usefulness to humans and you're not growing humans. Plants are more concerned with spectrum. All the lumens in the world won't help if they're green. Plants want blue and red. CMH has more blue than MH and more red than HPS.