Issues with High Temps in Grow Tent

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.

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

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

vostok said:

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

Click to expand...

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

If having trouble with heat must figure your "cmf's" for you grow tent

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

Just curious.....is your intake low in the tent and the exhaust high?

SSHZ said:

Just curious.....is your intake low in the tent and the exhaust high?

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Yes, intake is low and exhaust is up high.

harris hawk said:

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

Click to expand...

just this in my blog, no fears of heat burn with cfl's ..here:

https://www.rollitup.org/Journal/Entry/a-collection-of-diy-ghetto-blasters.30154/

Should the intake fan and exhaust fan be running at the same speed, or should one be slower than the other?

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?

T.C. Bosby said:

Should the intake fan and exhaust fan be running at the same speed, or should one be slower than the other?

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Correct - if that seem not to cause no heat issues - sounds like you have the equipment

T.C. Bosby said:

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?

Click to expand...

No - just do what your doing - covering the flood table could cause issues -

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.

blackforest said:

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.

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Both fans are 400 CFM with speed controllers.

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

SSHZ said:

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

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I always understood it to be the opposite...more air in then being exhausted...even tho I've never done that .

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.

skunkwreck said:

I always understood it to be the opposite...more air in then being exhausted...even tho I've never done that .

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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.

SSHZ said:

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.

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I agree totally on that !