Issues with High Temps in Grow Tent

T.C. Bosby

Well-Known Member
Alright, just started my first grow, and I'm already in trouble.

My current setup is a 3' x 3' x 6'11" tent. I have a 6 inch intake fan and a 6 inch exhaust fan. My light/reflector is the Phantom CMH 315W. The reflector is uncovered (no glass lid), so it is running a bare bulb.

I've had the light as far as 28 inches from the canopy and am hitting temps of 88 at night. The ambient temperature of my apartment ranges from 72 - 75 degrees.

I had hoped to keep the bulb bare so as to not block any UV, but at this point my tent is more an oven than a grow tent. There is a conversion kit available that changes the Phantom into an air cooled hood and makes it so that it is no longer a bare bulb. I'll lose some of the UV if I do this, but at this point my options are limited.

So here are my questions: 1) Given the ambient temp of my apartment, do you think going air cooled would resolve this issue? 2) I'm trying to keep costs down, so other than going with an A/C unit, do you have any ideas on as to what I can do to fix this situation?

I've read so many reviews of people stating they have their light 12 inches away from the canopy, so I just can't figure it out. Either I'm just screwing up big time, these people live in the Arctic Circle, or they aren't mentioning all of the details of their setup. Any help would be much appreciated. Thank you.
 

vostok

Well-Known Member

Leap to the glass cover /imo

UV I use only in the last 7-14 days

and only in poor weather, I grow in and out

good luck
 

MeJuana

Well-Known Member
Try making both inline fans exhaust and let intake be passive. If you turn the air over fast enough technically you should be able to have about a 5 degree difference. Air cooled hood helps
 

harris hawk

Well-Known Member

Leap to the glass cover /imo

UV I use only in the last 7-14 days

and only in poor weather, I grow in and out

good luck
Do you have one for CFL's - heard that 2-6 works well ? thought's ? know of some 500 cfls' - distance 3 inched from top of plant. using this chart for cfl's any where from 5-8 inches from top of plant
 

Growdict

Well-Known Member
I have a 4" exhaust with cmh 315. I only get 5 degrees diff. If i add a blurple i get another 5 up to 82 deg. Try without the filter, maybe it is adding too nuch resistance
 

T.C. Bosby

Well-Known Member
Another dumb question: The tent I'm using has a mylar fabric tray that goes at the bottom (water proof). If I were to cover that up, with let's say like a flood table, would removing that reflective surface help lower temps at all?
 

harris hawk

Well-Known Member
Another dumb question: The tent I'm using has a mylar fabric tray that goes at the bottom (water proof). If I were to cover that up, with let's say like a flood table, would removing that reflective surface help lower temps at all?
No - just do what your doing - covering the flood table could cause issues -
 

blackforest

Well-Known Member
You can fix all of this with the right fan setup. I see you are using 6" fans, what are the cfm's? Are the the smaller 190cfm, or the bigger 440cfm? If you use a big enough exhaust and a fan or two within the tent, you can keep it as cool as the ambient temp outside.
 

T.C. Bosby

Well-Known Member
You can fix all of this with the right fan setup. I see you are using 6" fans, what are the cfm's? Are the the smaller 190cfm, or the bigger 440cfm? If you use a big enough exhaust and a fan or two within the tent, you can keep it as cool as the ambient temp outside.
Both fans are 400 CFM with speed controllers.
 

SSHZ

Well-Known Member
I think the key is to create negative pressure, meaning the exhaust should be slightly stronger than the intake.......
 

skunkwreck

Well-Known Member
I think the key is to create negative pressure, meaning the exhaust should be slightly stronger than the intake.......
I always understood it to be the opposite...more air in then being exhausted...even tho I've never done that .
 

SPLFreak808

Well-Known Member
Two options....

1. Use colder intake air (a/c or pull from outdoor)
Or
2. Use a TRUE sealed hood with its own ventilation system.
 

SSHZ

Well-Known Member
I always understood it to be the opposite...more air in then being exhausted...even tho I've never done that .
That would not be negative pressure......what I told you is correct. I know about this from much larger room grows than small tents, but I imagine the principals are the same. It would also help if the intake is on the opposite side relative to the exhaust so the intake air has to cross thru the tent.
 
Top