Patriots781
Active Member
Hey I was jw tje furthest I can get my 750 watt hps above my plant is 10 inches is this too close or?, I have two exhaust fams hooked up to light
Height of hps
- Thread starter Patriots781
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StareCase
Well-Known Member
For the higher wattage HID bulbs, 16" - 18" is usually a good distance.
You can use the back of the hand test. Hold the back of your hand under the light at 16" for 30 seconds. If it's uncomfortably warm for your hand, you are too close. Keep moving your hand further away in 1" increments. When it's not uncomfortable after 30 seconds, there is your correct distance.
You can use the back of the hand test. Hold the back of your hand under the light at 16" for 30 seconds. If it's uncomfortably warm for your hand, you are too close. Keep moving your hand further away in 1" increments. When it's not uncomfortable after 30 seconds, there is your correct distance.
Patriots781
Active Member
its a super lemon auto from seedking
JoeBlow5823
Well-Known Member
Thats likely way to close and going to cook it. Is the light air cooled at least? I run double ended HPS now so its sort of a different ball game for me but when i ran single ended, my 1000w was at the top of my 5x5 (about 36'' from the plants) and this was the grow. All the ladies were very happy.
Renfro
Well-Known Member
Too close and all that infrared really pumps up the leaf surface temperatures. So yeah they will cook unless you can get the room cooled down to like 65 degrees or some insane number like that. Also with such low canopy temperatures the lower portions of the plant would be at a less than ideal temperature. Even if you get those temperatures under control, buds that get too much light can get chlorosis/bleaching on the tips and grow some really crazy foxtails. Pretty much trashing the top third or more of your best tops.
Kassiopeija
Well-Known Member
6-10cm distance per 100w HID... best is to keep an even canopy (middle spot preferably lower) by e.g. topping the mainstem, or scrogging
StareCase
Well-Known Member
... good Rule of Thumb ...
JoeBlow5823
Well-Known Member
For double ended HPS I would say closer to 5'' per 100w.
Kassiopeija
Well-Known Member
yeah well its sort of dependant on hoodform, spreader yes/no and lamp degradation... but 50'' is quite a distance... I wouldnt be able to use that in a tent that has a max height of 2m. or, only with a scrogg of some kind
JoeBlow5823
Well-Known Member
Its true for just about any hood. Most commercial growers keep them 5-8 feet from their plants. They are powerful as fuck. Im finding with the sun systems air cooled hood (the one that can be ran closest to the plants) even 36'' is to close. Getting a taller tent and making modifications to get it up another 12-18''.
Renfro
Well-Known Member
I run DE's in my basement and things get pissy when the plants get closer than 16-18 inches under the center of the light and like 10-12 inches around the perimeter. All sorta foxtailing and bleaching. Of course some strains like less light than others, the glue for example will foxtail like mad but doesn't bleach very easily. Mimosa will bleach at 20 inches center if the light is on 1000w or higher setting after day 45. So genetics has a lot to do with how much light is the max.
Kassiopeija
Well-Known Member
only the closed ones artificially exacerbate the middle hotspot, there are "spreader"-type of reflectors which accept some losses to level it more out. You can get closer then, around 15'' to under a 600w.
but the hooded reflectors do cost extra luminosity (extra glass) plus they arent able to do away with the HPS brutal IR output.
8 feet? 2.4384 meters? thats insane... itll more than double your cost/need of space. how is your ppfd at that distance?
Kassiopeija
Well-Known Member
hmm, Im getting an error message when trying to view that picThat cola there is about 10-12 inches from the light height wise and between the two lights getting hit from both sides. Turned out awesome.
JoeBlow5823
Well-Known Member
Oh yeah when you drop to a single end 600 or less you can get pretty close. Im taking 1000w double end bulbs... Either way, my light has to be hung really high to get a good even light spread. if it was in a 4x4, 36'' would be good but for my 5x5 i need to get it another foot higher.
That cola there is about 10-12 inches from the light height wise and between the two lights getting hit from both sides. Turned out awesome.
Renfro the tops of my fan leaves bleach, but they show no signs of too much heat... Is bleaching a problem? What does it hurt?
Renfro
Well-Known Member
Pics?
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