Pissed Off. Heat Killed Seedlings, Help

I have a 3x3x2 box that HAD a 120w LED in it... had a small fan from walmart, and the LED has three build in fans. The temp in the box got to 105 degrees farenheit last night and killed my AK47 x New York and Blueberry seedlings. What kind of fan should I buy to keep it like 70 degrees in the room? Room temperature is only 67 so i dont know how it got so fucking hot. Damnit I'm mad. Also, the fan can't really let off too much noise.

ANYTHING I can do to keep it cooler in there would be greatly appreciated. Are CFLs significantly cooler? How hot would it get in a box of that size with little ventilation with some CFLS?

100f aint much mate mines 100c

How are you getting 100 F + temps with an LED? Do you have ventilation in there?

CFLs are hotter than LEDs. I use both.

Green Inferno said:

How are you getting 100 F + temps with an LED? Do you have ventilation in there?

CFLs are hotter than LEDs. I use both.

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I didn't have ventilation in there just a fan and the three fans on the LED. Maybe mine is defective. Still didn't think the temps would get over 100

LetsRollABlunt said:

I didn't have ventilation in there just a fan and the three fans on the LED. Maybe mine is defective.

Click to expand...

You gotta have a vent for fresh air to come in, and an active fan to take out the stale hot air.

My LED has built in fans too, but if I do not have my exhaust fan on, it gets pretty hot in there. With it on,
it stays right around 77 F.

Not only the heat killed your plants, they also suffocated from lack of fresh air.

you definitely require a source of fresh air for ventilation...

Lack of fresh air shouldn't kill seedlings over a 5 hour period though, right?

it does when you are running electrical equipment in the closed environment....something about thermodynamics and no electrical system being able to not put out oodles of heat while operating...not really sure to be honest

you know all to well now....unfortunately...they be roasted...

CFL's will not solve the issue...it will merely hasten the death of the next batch....
you need lots of fresh air at the very least to move heat out of the system...

open it and let air in.

it's not a matter of suffocation...the air we suggest...

....air is a handy way to move the heat roasting them to death created by ANY light system
it's a basic requirement for any grow to succeed.

Ok that's what I figured chubby, thanks. Although I do think the T5 fixture I have stays cooler than the LED (which was purchased through HTG-Supply)

if i may suggest running the system with no plants to monitor the temps before sending in new seedlings/clones?

it may save some heart ache... or give a clue how close you need/want to fudge stuff

I'm actually doing that right now with a single t5 lamp to see what the temps get up to... so far its staying around 75. With just a few minutes with the LED it was up over 90. I think I'm going to purchase the 4 2ft T5 fixture.

You can get an inline duct fan for like $20 and it would take care of your heat problems.

pretty sure even a passive inlet/outlet correctly placed/made would assist you a great deal in your endeavors
even prevent light leaks all the while if that sort of fairy tale makes you ill at ease even.....light has a hard time making right angle turns

think of it like this...they already have to give up sunshine(it really is the best), root size(stuffed in a pot), and elbow room (stuffed in a box) for your nuggies
they need proper good food/water(...not sausages or turkeys...so no need to stuff them), light (wild debate), and lots of nice fresh perfect air(temp/humidity) before they even have a chance...
who wouldn't given those circumstances i would figure...lol




good luck to you

Ok guys, so I'm going to make a box instead of using my current area.

For all of you that know your ventilation, maybe you could help me out. So if the dimensions are 19" x 26" x 22", and I cut an inlet in the bottom with a 4" top exhaust (computer) fan rated at 85 CFM, what would my lighting options be to keep the temps at a normal level? Would this space be too small for HID lighting?

yes...HID might be a bit much for that... not to terrible good at the numbers thing...perhaps i'm wrong
seems awful small for one... i sense scorched plants ahead with those


19x26x22= 10868 cubic inches
10868/1728 (number of cubic inches in a cubic foot)=6.28 cubic feet to work with?

under cfl/t5 you could probably get away with 1 full exchange of air per 5 minutes i would venture a guess to deal with heat...
five times a minute is more where the HID crowd goes in my experience...
more air isn't gonna hurt the plant unless it's whipping around like a hurricane in a pc type of grow though

i'd call it 31.4 CFM as a requirement for that space...85CFM pc fan should be fine
you'll need the extras for scrubbing odors later anyways