ventilation problems

[stoner 420]

I have a grow box that i made for an old armore and i am haveing problems with temps getting too high... i only use cfls cause i don't have the extra cash for a hps light ... i have been looking for a cheap 250 or even a 70 w and add a couple cfls... but n-e-ways i have 9 26 watt for veg and 8 26 and a 42 for flowering.. i have four fans one intake one exhaust and two circulation fans they are 4.5 inch fans u get a wally world for 5 bucks i changed the pitch of the fans for higher cfms ... the intake is in the bottom left corner and the exhaust is in the upper right ( not quite the corner) the temps get to 93 and i can only get them down to 85 for a short period.. i can not leave the door open i am renting ... if anyone could help me with some inexpensive suggestions or some pics of ur grow box ... the size is 30'' wide x 18'' deep x 46'' tall... anyone with a box about the same size with pics would be great........ thanks for your time

 

[4u2sm0ke]

well mine is not nearly as small as yours..It does not realy matter what size box..you Have to exhaust in order to remove heat..now you said you have 1 exhaust in upper corner...but you dont know what one..lol..I say add more exhast in top of box..one more corner ...or straight out the top...Hope this Helps ..if not well I helped bring it back for some fresh eyes....

420

 

[kailiwela44]

i agree w/4u2smoke.
i have a box ~24x14x24". I have 6-40 watt bulbs. I have one intake powered by a 4" walmart fan (located in the center and back) and two cpu fans for exhuast (both on the ceiling, one right back corner, and front left corner)--i should have had the passive intake on the bottom in the middle and maybe a four corner or two side exhaust set-up. I have a difficult time with temps too.
Maybe you should cut another exhaust, across your current exhaust, and use one of your circulation fans for exhausting. Or, you could have two exhausts and use a passive intake system--twice the size of your exhausts creating negative pressure.
If your ventilation is good your temps inside the box should be a few degrees above the ambient room temp (ambient temps play an important role also). If you cannot get this tuned up then maybe you should see how you can work around it. I use C02--sugar yeast and H20 good for temps 85-95F.

good luck,
kailiwela44

 

[420FREEDOM]

If the air in your rooom is hot (above) 80deg, you'll never get the cab cooler than that. Try cooling the air from the room. If the room air is nice, then you need more ventilation. Also grow cabs still need an oscilatiing fan to keep the leaves moving. if your leaves aren't moving, then they are not getting getting good air (co2), and plants will have little growth. A marijuana plant uses all co2 next to its leaves in about 3 minutes, so the air needs to be constantly refreshed.

 

[stoner 420]

thanks all for the info.. the room that the box is in is 71 degrees so i don't know why the temps are so high..there is deffinately enough air exchange in the box i think that is why my rh is so low ( 25) i took a couple of pics to show yall my fan setup and some of my plants that are 22 to 24 days old and this is all i have it is frustrating.. i got mad and turned the box off cause they did not grow any all weekend so i turn it off for 24hr and come home today to see they grew some so i turned everything back on... pls tell me what u think i should do to change my bad luck...

if u store ur seed in a prescription pill bottle that u did not rinse out can it cause problems to the seeds thanks for the help..........

 

[Leeguana]

First, I would lower the lights to an inch from the plants.

Then try taking the fan out of your intake (or just don't turn it on) to make it a "passive intake". And use only one fan to circulate air around the plants. That exhaust fan looks plenty big enough to suck the warm air out of that little room.

My grow area is about 1/2 as big as yours (though I have a few more cfl's), but this is the ventilation setup I use, and the temps max out at 80F. And the room where my grow cabinet resides is maintained at about 76F, around the clock.

Let us know what changes you make and if your temperatures go down.

Peace.

 

[stoner 420]

thanks leeguana .. i have tried the one exhaust and two circulation fans temps went up quick.. i tried just intake and two circulation fans same result temp up very fast... the only thing is the fans i have for circulation are not powerful enough to use alone i have to have both to reach all the plants.. as u see in the pics the two circulation fans are now setup where the one infront of the intake blows it across the plants and to the other fan which blows it to the exhaust fan ... i will try but i am almost sure it will not be enough air circulation... thanks for the input and i am epecting more for everybody i am in serious need of help with both ventilation and the slow growth.... thanks to everybody that is helping me sort this out.......

 

[Leeguana]

I misread the dimensions of your grow area. Mine are actually almost identical - 2 1/2'W x 2'D x 4'H, and a very similar setup.

I only have one passive intake near the bottom, one exhaust hole near the top with a fan from a broken microwave blowing out the warm air, and a small cheap fan on the floor (set on LOW) for circulation. As I kept adding lights, the temp kept increasing. It got well over 90F for a day or two until I attached the exhaust fan to the side wall, and now it never gets over 80F anymore.

Here's a pic of the side wall that has the exhaust fan attached. That exhaust fan and the little white plastic fan on the floor are all I use for air movement.

 

[420FREEDOM]

Do you have to grow in the cab, If your room air is fine, you could just keep em in the room, and when you want to flower put them in the cab or a closet or put a hevay blake drape to cover them

The cfls must be getting hot enough to rise that tempertaure. You could put your small oscillatiing fan in the cab to blow up onto the cfls pushiing the hot air upward quicker

 

[stoner 420]

thanks to all .. 420freedom i have to grow in a cab as i stated before i am renting so they can not be in view.. and also i do have a fan blowing up towards the exhaust fan .. thanks but i am one step ahead of you.. leeguana i like the idea the fans on the side. but only one problem i need stealth and can't find an idea to trap light from the fans or i could do what u did and put anywhere... good news is after i turned the lights off for 24 hrs the temps are staying around 84 with 30%rh so i guess everthing saw i was mad and started to work right.. yahhhhhhh the fans are working considering all the fans ... thanks everyone for the info but one intake or one exhaust just is not going to work for some dang reason .. i also think the fact that the box is on an inside wall makes a big difference.. and if i lower the lights the temps get way too high like 100 so thanks but not gonna work..... thanks agian everyone.......

 

[stoner 420]

ok i found the only reason for the temps down was cause my a\c was running all the time.. i am curious if i took the intake fan and hooked a flexable dryer duct to it is that what u call passive and would it increase cfm or suction.. also should i just add another intake fan or an exhaust ...

 

[andy52]

i have a tent that is 2x2x4.i use for veg with a 400w mh.i have the exhaust blower inside the tent,drawing air thri the charcoal filter,then thru the reflector,then out the top into my basement.i have a 180cfm blower at the bottom front corner,drawing air from my portable ac unit into the tent.keeps it pretty much anywhere i want it.i keep it around 72-78 degrees.hope this helps.good luck oh,also a oscillating fan inside the tent

 

[stoner 420]

thanks andy but this does not really help cause i don't have a MH reflector.. my box is not big enough to put blowers in i tried to put a high pwer vortex fan in there that i got a wally world and it was way to big .. thanks any ways pls someone help me with this .. this is getting annoying.. can any one show me pics of a DIY passive intake or exhaust system... this should create more suction .. pls help i am in serious need.. i can't get a grow going and i really need to be growing for my medicinal reasons.. thanks to everyone that helps or that has helped......