heat

[polpolno1]

Hi
I just started growing have a small cabinet
60*70*180 cm I'm using 4 floracent ho light that gives 26500 luominm.
I us a 130 m^3/h fan, I have 2 plants two weeks in vegging time they look good.
My problem is the heat and humidity.
The heat is between 31 to 20 degrees Depend on the wether out side,the winter didn't came this time but in one to two weeks will get cold.
The humidity is between 25-35%.
I'm gooing to buy a cold vapor.. .
What I don't understand is why the fan don't maneg the heat it should change the air every mint....
Any body have a suggestion?if I buy a bigger fan it would help? Some thing else
Thanks

 

[sunakard2000]

130 cubic meters per hour? wow thats low, that comes out to what about 2.166 cubic meters per minute, thats insanely low, the fan that i use to cool my light is 424 CFM and if i did the math right thats about 144cubic meter per minute, yours is really low, heck the small bathroom fan i have installed in my veg closet pulls 60CFM, your defently going to have to look into a better ventilation fan.
by the way the humidity is fine, granted it NOT the target zone but LOW humidity is ok but HIGH humidity is BAD BAD BAD, if your naturally getting low humidity its not really a big deal, wont have much of a noticable effect on the plants, just keep it below 60% humidity and youll be fine, but still your going to need a better fan for exhausting your area, that 130cmh aint gonna cut it.

 

[Hushpuppy]

I think the problem is that small contained grows are subject to external atmosphere conditions. The low humidity is causing large temperature swings. The exhaust fan is more than adequate for your grow and may actually be too much. You need to get the temps to be more balanced between 23-27c. Also, while in veg, you don't need to turn off the lights, which leads to the colder temps in the space. MJ only needs dark period during flowering.

I think your problem is partly in where you have your grow cabinet. The environment outside of your grow will need to be controlled better to keep the cabinet in a better range to temps and humidity. While 25-35% humidity is a bit low for MJ, its not critical, but you do need to get it to about 50-60% for best results. Many people use a closet or built cabinet, or a tent, all set in a spare room of the home, or in an external building from the home. You will have to control the environment within this space to get the grow environment under control

 

[Hushpuppy]

Sun; I think one of us figured wrong. I came up with that fan totally cycling the air in that cabinet 2.8x per minute. That space is very small, about 3/4 of 1 cubic meter, and the fan is moving 130 cubic meters per hour, which is 2.86 cubic meters per minute. That should be more than enough air movement

 

[polpolno1]

Hi
First thing you guys are unbelievable!!!thank you for the help.
Forgot you don't use the metric system...
The fan cycle is 2.1 cubic meter every one minute
The closet is 0.756 cubic meter it's mean that every minute the air is changed twice!!!
From what I read here its more then enough... but still the temperature is too high.does it make sence??
The closet is in my small house and I don't need to cool or heat yet, its only beginning of winter here....
One more thing, I covered all the closet inside with mirrors, could it be the reason for the over heating?
Thank you again

 

[sunakard2000]

mirrors are terrible, they reflect visible light but absorb the energy photons the plants use for photosynthises, with that being said, take out all mirrors and do one of the following,
Paint walls FLAT WHITE,
or
Line walls with Mylar.
the paint and mylar REFRACT the light meaning it actually bounces off, light and energy photons, where as the mirror absorbs the important part of the light only reflecting the visible light without the energy photons, also yes mirrors absorb heat and hold it quite well.
yeah sorry we dont use meteric here, i typically dont deal with anything more then mL, L, and grams the basic stuff lol, dont remember all those conversion rates lol but yeah looking back defently enough exchange. so your good on the ventilation, its gotta be those mirrors, also as wierd as it sounds an oscillating fan in the room your tent/cabinet is in helps keep good air movement in the room, which could help keep temps slightly more even, helps reduce cold or hot spots in a room. pretty much just helps keep things fresh and moving even outside the cabinet or what ever your growing in.

 

[polpolno1]

Hi
Like hushpoppy said the environment is the most importent....winter came here last day at the afternoon and the temperature is good from 27 to 23 I think I'm ok till June....
I don't know what to do with the mirror now ...
They glued to the cabin by a carpenter so it's really glue it will be hard to take off I can paint with wait color on them or put mylner....
Is it that important? ?

 

[Hushpuppy]

Either get some mylar and some double sided tape and cover those mirrors or take some cardboard and paint it real good with flat (brilliant) white paint and cover the mirrors. Don't keep using the mirrors as they are robbing your plants of light energy every hour the lights are on.

As I said earlier, maintaining the room temps and humidity will be key to having the cabinet do well. Also, unless you have people or animals in the room continually to provide CO2, you will need to pull fresh air into the room and exhaust the grow cabinet air outside the room.

If cold temps in winter become an issue, you can use candles or small propane/natural gas burners to provide both heat and CO2 for the room. However, please be very careful when using fire for (obvious reasons of hazards) but also for both co2 and heat as this method is not metered to give exact amounts of either co2 or heat. If you do this, you will have to monitor it until you get the right settings so that you don't create too much heat or co2 within the room.

Once you switch to flowering where you have 12hrs of dark time, you can conserve heat within the room by cutting the exhaust fan off periodically. I recommend having the exhaust fan on a timer to allow it to come on for 15min every 2hrs during the dark period so that humidity doesn't get too high. Then set the timers so that the fan comes on a few minutes ahead of the lights so that there is fresh air in the space when the lights come on. Then have the fan stay on for 10minutes after the lights go off to cool the lights.

 

[The Hemp Goddess]

If you are not pulling in air that is cool, you are not going to be able to keep your space cool, regardless of how many cfm your fan is.

 

[WeedHopper]

I agree with THG. You have to pull COOL air into your growroom,,,and pull the hot air out,,are you will never keep temps down.
And if those mirrors are worthless to you,,paint right over the basterds. Flat White Paint,,I use SW Extra White Flat. up to 97 Reflextion Value.