Heat problem in growbox

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amsterhamster

Well-Known Member
So, it was time to move the seedlings closer to my lights. After moving them, my surface-of-soil temps shot up to 90.. What's a good cooling method for this?

It's in a rubbermaid box setup, one intake at bottom and an exhaust at the top. Had been keeping things VERY cool before, but now that my seedlings are 2" from the CFLs it's very hot, or at least the thermometer says... the air coming out of the exhaust feels cold however.

Any tips? +rep
 
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dbo24242

New Member
If its really that hot your plants are probably too close and at risk of having some damage done to them. the exhaust may not be gathering the right air and the thermometer may be misreading because the light is heating up the liquid inside of it. Try covering the thermometer with a piece of white paper and checking it. if it feels hot it is hot, but it sounds like a funky reading to me. stick your hand in there and see if it feels 90 degrees
try putting a hole near the bottom of the box so there is circulation for the exhaust, it will be pushing air out which it has pulled in through the bottom.
ambient temp? wattage of cfls?
 
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amsterhamster

Well-Known Member
SCORPIO13 said:
do you have a small fan in the circulating the air?
Click to expand...
Didn't know I needed one.. here's my setup.. humidifier (cool) blowing into intake fan, with exhaust fan at top. 6 23w CFL 6500k and 2 42w CFL 2700k. Entire thing is coated with flat white spray paint then has a layer of mylar over that.
 

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SCORPIO13

SCORPIO13

Well-Known Member
That fan looks big enough to do the trick by itself. Like dbo24242 said maybe they are just a little too close. also try the paper over the thermometer to see if that might be the problem. I have a small 6" fan blowing cool air between the lights and the top of the canopy.
 
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amsterhamster

Well-Known Member
It's an 8" fan.. or 10", something like that. The air that's coming out is nice and cool so I don't understand.. I mean, I don't know anything about thermometers but it's brand new, could it be broken? It seems to think my humidity is only like 36% even with the humidifier INSIDE of that small space.. doesn't make very much sense. But anyways, before moving them, I was able to achieve a steady 45% humidity with 76 to 80 degree temp.

I've been told for good growth it should be 2 inches from the cfls.. Right now I moved them back to the bottom of the box cause I don't wanna burn em.
 
SCORPIO13

SCORPIO13

Well-Known Member
you should be as close as possible to the cfl's but if you are get 90 degress then something needs to be done. Check your thermometer.
 
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amsterhamster

Well-Known Member
well, I have a light meter that goes to 2000 and directly under all my CFLs it is BARELY under 2000 (im not sure what kind of unit they use for measurment). When I have it at the bottom on top of the plant pots, it's 1200.. is that really that bad? also, what "paper" over thermometer? what's that do
 
trombon84

trombon84

Well-Known Member
i grow with cfl's and I have kinda the same prob with my thermometer .... or temperature. If the thermometer is to close to the CFL, than the temp will be around 90-92. When I put the thermometer somewhere else in the room .... than I have 80.
It is normal and logic; as closer as you get to the lights, as hotter it is
 
buenodiasmf

buenodiasmf

Well-Known Member
i had the same problem inside my rubbermaid...i got an internal 6 inch clip fan .. the circulating of the air plus the intake of a pc fan and exhaust of a pc fan did the trick...temp dropped humdity dropped... and the walls stopped sweating...buds have never been happier:weed:
 
Resident Kush

Resident Kush

Well-Known Member
use vent holes or slits in the lid of the rubbermaid, if thats no good point the fan upwards so its bouncing off the top.
Or change the fan into a small air conditioner ...
 
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