How close is too close?

Beansly

Beansly

RIU Bulldog
In deciding how close to put your lamp to the tops of the plants, is temperature the only mitigating factor. Can plants get UV burn if you put them too close?

Cause I got a sealed, air-cooled, 400 watt light hps set up that i swear, is like 85 degrees four inches from the glass. And I know that lumens are lost really quickly with ever inch. I keep bringing it closer and closer until I stopped at about 7-8 inches. That's as close as my head will let me go for now. So any input?
 
jeffchr

jeffchr

Well-Known Member
7-8 inches is too close IMO. my friend's lamp is not air cooled, but it is 400w and he keeps it 1.5 - 2 ft. he has a lot of air circulation. there is very little heat at the top of the plants. they dry out and burn quite easily. peace.
 
Youngling

Youngling

Active Member
I actually am using a yield master 2 hood with a 400w hps inside a dr 60 (2ft x 2ft x 5ft) the highest temp I get is 86 average temps are 82 - 84. The buds are about 1/2 inch from the glass with minor heat stress from before I fixed my temps.

To get temps this low I have the A/C ducted into the tent and two fans pulling air from the hood I do have the glass on the hood.

I'm also down south so thoes up north may have less heat issues.
 
B

bobhamm

Active Member
Beansly said:
In deciding how close to put your lamp to the tops of the plants, is temperature the only mitigating factor. Can plants get UV burn if you put them too close?

Cause I got a sealed, air-cooled, 400 watt light hps set up that i swear, is like 85 degrees four inches from the glass. And I know that lumens are lost really quickly with ever inch. I keep bringing it closer and closer until I stopped at about 7-8 inches. That's as close as my head will let me go for now. So any input?
Click to expand...
well,HPS puts out very little UV from what I understand, and yeah its mostly temps, too much light could cause leaf bleaching , that being said I have a 400 watt CMH bulb in a turkey roaster pan 7 inches from the top of my plants and they are doing just fine air temps of 77-80 F
 
S

smalltownfella

Member
Let your plants tell you how close is too close. If they start to burn, they will let you know and you can adjust. I have plants resting on the light tube itself and doing ok. It's not just weed, it's a weed and quite resistant.
 
Beansly

Beansly

RIU Bulldog
Thank for feedback. I think that since most people use bigger lights, they dont realized how much air-cooling a 400 watt light decreases the heat (literally 28 degrees w/o the blower). As long as theres no issues with UV, I think im gonna keep bringing the plants closer until they tell me not to.
 
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