Grow room heat problem

I have just started up my 400W MH bulb on my six seedlings but I've hit a heat problem - my temperatures are hanging around 100 degrees or so, and all I have right now is one fan for ventilation/air movement and I keep the closet doors open at all times. The temperatures are definitely too high and I don't have the hardware or the budget to cool it down. I have no car so I can't go to a store to buy an AC unit, and it's too conspicuous to have one shipped here (my parents would wonder why I spent so much money).

Your advice?

Put away the MH and just grow with cfls for now...especially for veg. Seedlings really dont require much light and a few 6500k cfls will do just fine plus will have very little heat. I can understand if you want to flower with hps but you will have to figure out how to handle the heat before you do that...100 degrees is way too high even anything above 90 is too high i think. But if you can't do any of that just grow throughout the whole process with cfl's....you can still grow nice plants.

yea i have to agree, u can rig up a cooltube like i did today its pretty easy just go buy a duct fan (but make sure its over 300 cfm or it wont do much for ya) and duct it to a glass tube thats safely secured to ur lights housing and direct the hot air else where

i have 2 little girls under 2 CFL's from seed and am shocked at how well they are growing. Had to top one of them already. I suggest switching to cfl's for sure. even if you have a ton of little ones you should be okay for veg

yes buy a cool tube , or u could just cut some glass to size and hang it infront of the MH to stop the heat from hitting the plants...aslong as your exhuast fan is uptop with the heat then your good to go.otherwise u will have to wait to winter to grow your weed were temps wont be so high

RC7 said:

Put away the MH and just grow with cfls for now...especially for veg. Seedlings really dont require much light and a few 6500k cfls will do just fine plus will have very little heat. I can understand if you want to flower with hps but you will have to figure out how to handle the heat before you do that...100 degrees is way too high even anything above 90 is too high i think. But if you can't do any of that just grow throughout the whole process with cfl's....you can still grow nice plants.

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I only have four CFLs and I can't go out and buy more stuff. I've blown my budget. Can't I just add a window AC unit into the grow room to solve the heat issue?

spencer2121 said:

yea i have to agree, u can rig up a cooltube like i did today its pretty easy just go buy a duct fan (but make sure its over 300 cfm or it wont do much for ya) and duct it to a glass tube thats safely secured to ur lights housing and direct the hot air else where

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That only works for reflectors that have ducting flanges. Mine is simple and cheap and is just a reflector. Also, duct fans are very expensive. And I don't have a glass tube or know of any kind that would "safely secure" to my reflector hood.

chasmtz said:

i have 2 little girls under 2 CFL's from seed and am shocked at how well they are growing. Had to top one of them already. I suggest switching to cfl's for sure. even if you have a ton of little ones you should be okay for veg

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I only have four.

smallclosetgrowr said:

yes buy a cool tube , or u could just cut some glass to size and hang it infront of the MH to stop the heat from hitting the plants...aslong as your exhuast fan is uptop with the heat then your good to go.otherwise u will have to wait to winter to grow your weed were temps wont be so high

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I don't have the tools or material to cut glass. Wouldn't lexan work just as well, if not better? Anyway, this would overheat the bulb since there is no way to attach ducting to the hood.


Why can't I just add an AC unit in there?

Exhaust fan with ducting, sucking hot air from the grow closet and the main room and into another room/outside. About $60.

That might help, I can make the ducting go right out into the crawlspace with the other hot air, and something like that would keep the hot air in there instead of coming in. Where can I get one of those for $60? Online? Getting to a store is tough, I don't have a car, but if I'd save a lot of money buying one at a Home Depot I'd do that.

Got a specific model number or something?

Btw +rep, good idea, simple but effective.

Squirrel cage fan, put it on the outside of the grow box with a hose going inside the box and it works very well to cool.

Centrifugal fans are very expensive. Is there a specific model you are suggesting?

If I bought this (240CFM) 6" inline fan and added some ducting, wouldn't that work even better with the higher volume of air it moves? http://www.amazon.com/LED-Wholesalers-GYO2402-Hydroponic-Booster/dp/B003YFADW8/ref=sr_1_5?ie=UTF8&qid=1310056169&sr=8-5

RC7 said:

anything above 90 is too high i think.

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i think you're wrong on that.....

caligreenzzz said:

i think you're wrong on that.....

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What's the highest acceptable temperature where a mj plant will still grow?

caligreenzzz said:

i think you're wrong on that.....

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i'm talking about ideal temperature....i've heard cannabis grows best around 80 degrees F or so

I don't even know the temperature of my grow room. My meter maxes out at 100 and the needle has been sitting as far as it can go all day. My plants don't seem to be growing as much as they should and I can't lower my light until my new reflector comes in. Never buy a HID reflector without exhaust options... that was the worst mistake I made.