How far should hid lights be from plants

M

MaritimeHigh

New Member
I just recently moved from a skrog led lightting to a 400w hps system to finish out the rest of the plants veg and flower. What would be a good distance to have it above my plants ?
 
dopeleader

dopeleader

Well-Known Member
Google "hps foot candles" I think it should be around 6-7 inches from your canopy but the pictures will tell you.
 
Budley Doright

Budley Doright

Well-Known Member
MaritimeHigh said:
I just recently moved from a skrog led lightting to a 400w hps system to finish out the rest of the plants veg and flower. What would be a good distance to have it above my plants ?
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Depends, is it in a cool hood or reflector? If it's a reflector I keep mine 16" away with a lite breeze flowing in between it and the canopy, at 6" you'll have nice toasty brown buds :o, I don't run cool hoods so have no clue :(. Check with your hand, if it's too hot on your hand it's too hot for the plants
 
dopeleader

dopeleader

Well-Known Member
6"-8" is your optimum height from canopy to light with a 400w as its HPS not MH, if you have a cool tube no problems at all if you don't your gonna want an oscillating fan moving that heat.
After 8" you really start wasting your light as it becomes useless light.
 
M

MaritimeHigh

New Member
OK thanks I'll give it a try and it's a reflector so I have a small fan blowing on it and a small tower fan blowing on the girls
 
dopeleader

dopeleader

Well-Known Member
The best advice I can give you is to set the plants at around 12" and lower it by an inch everyday until you see evidence of heat stress.
Because you want your lights as close to your plants as possible without them being harmed, the further they are even by per inch the amount of light u lose is alot
 
Budley Doright

Budley Doright

Well-Known Member
dopeleader said:
6"-8" is your optimum height from canopy to light with a 400w as its HPS not MH, if you have a cool tube no problems at all if you don't your gonna want an oscillating fan moving that heat.
After 8" you really start wasting your light as it becomes useless light.
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I would need a shit load of air moving over the canopy to keep the plants from burning at 6" and I know that because my fan quit two weeks ago and yup burnt the crap out of a few at 16" away :(.
 
M

MaritimeHigh

New Member
Since I put the new light in their was a lot of moisture and condensation so I vented the tent but my plants have drooped any ideas what it could be ? I feed them remo brand every other day and follow their feeding chart and water in between feedings pH is around 6.8 and I'm using distilled water
 
racerboy71

racerboy71

bud bootlegger
MaritimeHigh said:
Since I put the new light in their was a lot of moisture and condensation so I vented the tent but my plants have drooped any ideas what it could be ? I feed them remo brand every other day and follow their feeding chart and water in between feedings pH is around 6.8 and I'm using distilled water
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have any pics of them? sometimes they might react a bit different switching light sources like you said you did, should bounce back after a few days time..
 
dopeleader

dopeleader

Well-Known Member
You will need an exhaust and intake fan to cope with the heat and humidity you add to the tent by putting a hps light in.
Because it evaporates your medium without correct air flow your tent walls will always be wet.
You NEED A hygrometer which will tell you the relative humidity and temps at any one time.
The plants wilting was probing a heat stress issue or even overwatering heat stress and humidity.
 
dopeleader

dopeleader

Well-Known Member
Try to take pictures without the lights on as its impossible to see.
However focus on lowering the temps and humidity and rule out over-watering and I think you'll be fine.
 
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