400 watt hps with glass and exhaust distance??

C

cannabisgreen

New Member
hi all i know this question probably been asked a million times but im gunna ask it again what distance should my light be from plants my light has a glass shield and a exhaust fan on the top of light pulling hot air out its a 400 watt hps was going off this chart http://www.thctalk.com/gallery/data/500/HPS-Light-Distance-Chart.jpg but is this chart without a glass and exhaust reason im asking is cause my girls r monsters and im running out of height im 2 weeks into flower today there about 3or 4 inches away still got some heightroom 2 work with im really bad with judging the palm 2 light trick how can i tell if there 2 close what do you guys keep your 400watters thank you!! to thoses that reply any questions ask away temps r at 79/81when light is on
 
sheldonblack

sheldonblack

Active Member
cannabisgreen said:
hi all i know this question probably been asked a million times but im gunna ask it again what distance should my light be from plants my light has a glass shield and a exhaust fan on the top of light pulling hot air out its a 400 watt hps was going off this chart http://www.thctalk.com/gallery/data/500/HPS-Light-Distance-Chart.jpg but is this chart without a glass and exhaust reason im asking is cause my girls r monsters and im running out of height im 2 weeks into flower today there about 3or 4 inches away still got some heightroom 2 work with im really bad with judging the palm 2 light trick how can i tell if there 2 close what do you guys keep your 400watters thank you!! to thoses that reply any questions ask away temps r at 79/81when light is on
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It's all about temperature, check the temp on top of ur plants and keep it below 80-85, also the closer ur light to plants, the less coverage for the plants not right in the center, I hope u get it.
 
jarvild

jarvild

Well-Known Member
I run my plants under a 400 with no glass and no air cooling of the hood at 8", I would remove that glass and gain another 10% of light that gets eaten by the glass.
 
G

GreenTrend2013

Member
I have 400 watt Also. My temps where about 91 degrees with my MH Bulb is 8inch way. The temps go down to 86 degrees when i move it 16 -22 inchs away. Which is better to get the light closer and have higher temps or further away with lower temps. My babys are seedlings
 
jarvild

jarvild

Well-Known Member
The problem with a 400 is you are really only getting about 2' of penetration into the canopy, My 400 mh runs cooler than my 400 watt hps , I have a 2'x4' cabinet with a 8" oscilating at canopy level and a 4" duct booster fan with a canopy tenp that never goes over 82 degrees.
 
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