Ventilation problem

hey guys.. hoping some one can help me on this thread.. since my last couple ones just disappeared with no replies..

basically i got a 70cfm bathroom fan the other day and hammered the shit out of my ceiling. i found a whole bunch of nasty ass shit in there.. which i think is some sort of cheap insulation. it's an appartment, but i vaccummed out a lot of it and made a 4-5 inch hole and I can see the actual ceiling now. i took a little exhaust ducting and tied it onto my fan and pushed it through that 5 inch hole. so all the air that is being sucked up, should just go out into the ceiling, and the crap inside should block the hot air from coming back down.. i made an intake hole at the bottom, but no fan there. it's pretty ghetto right now, but i blew all my money on the fan and didnt have enough to buy a piece of wood (which is what i will do later) and there are 2 computer fans stacked on each other to push the air up..

my grow room is a 2 door slidingdoor type of design. i have a whole bunch of panda film sealing off the 2nd half of my closet. im using the left side for the grow, right side for clothes and boxes of crap. the whole closet is 8x8x2. - im only using 4w x 8h x 2deep for the grow room. it's not COMPLETELY sealed, but its good enough - no light leaks or anything.

anyways, my problem is.. it's not really working. the temps are still kind of high in there.. 80 with cfl.. i know its not a problem, but i am planning on getting a 250hps for flowering and if its 80 with cfls.. oh man.

i got some pictures up.. i also made a fast image to show every1 what it looks like in the ceiling.

please guys just throw me some advice... thanks!


-the lights are tilted because i want the other plant to catch up in growth..

have i done something wrong?

dude just buy an 89dollar growtenton ebay, it will save you a huge hassle and you dont have to cut into your apt

Blaze 250W of HID in a 4x2 is going to generate some serious heat. I don't think that your bathroom fan is going to cut it. On top of that, when they go into flower they are going to generate some serious stink and you are in an apartment. Are you going to air cool the light? If not I would consider that and put a scrubber on the intake side of the light to address the stink. With that said I still think that you will need to move more air inside to keep the temps down. Good luck!

Actually, if I get the 250w, it has a shitty hood - its not air-cooled and ballast is built in. I found a deal for a 400watt HPS with an air cooled hood and external ballast. I am going to be getting a 160cfm fan from home depot and run ducting and boost the air out through that fan. The bathroom fan I got for the room has 70cfm and the booster is 160. I know they don't stack, but my theory is that I will suck out the heat from the air-cooled hood with the 160cfm really well and then it's going to go up into the ducting that will be mounted onto the bathroom fan I put in. that will suck a little bit more, and then I have the exhaust of the bathroom fan shoved into that little hole I made. There is about 2ft of insulation and then 2-4 ft more of free space until it reaches the pyramid-shaped roof. Then on the outside, I looked and there are a ton of fans and pipes in the roof. I think about 5-6 fans and 8-10 pipes just shoved into the roof. I'm guessing the design is just hollow inside with some of that insulation and then the heat rises out of the pipes and fans.. lets hope so!

Also, thanks for the scrubber idea, I was wondering about that. Would the smell go out that far? I thought it would just be the room that it's in. The sliding door closet is in my room, about 8-10 ft away from the sliding glass door window. I am a MMJ patient, but not sure if that would cover it in an apartment. Where could I get some of the carbon scrubber cheap? I wouldn't mind if it would run out after 1 grow.. I need to finish this grow.. and by then I'll get some extra cash to upgrade everything - like a real inline fan with 400+cfm.

One more little question, for my air cooled reflector, could I block one end, and then put the inline on the other, run the ducting all the way up to the bathroom fan I put in? Would it work if I just blocked off the other side like that?
And then when I get the carbon, just put it in between the ducting and inline.


And if all fails with heat... I have a back up plan. My 12000btu+ portable air conditioner. I got a couple of years ago for like 700 bucks.. crazy. But I hope I can avoid using that.. it uses up 1200watts LOL

Hey man, that 160CFM booster fan will be pretty much useless. Booster fans are designed to be inside ducts where the air is already moving. That's where their CFM ratings come from. They are NOT very well suited for moving static air. Even coupled to your bathroom fan it will be useless. I highly suggest getting a 165 CFM inline fan, as it truely pulls its advertised air. Its like 60 bucks before shipping(https://www.rollitup.org/grow-room-design-setup/342580-best-deals-thread-updated-version.html#post4318490). This is one area you dont want to skimp out on. Especially if you plan on hooking up a carbon filter to the fan, you will need an inline.

I would love to get an inline fan. I know that they are really great, like 400 cfm 6' or even 800cfm 8'.. but it's just I don't have ANY cash right now. I'm tryin to sell my glass pieces for the HPS light.. hahah. I was thinking of something new,
what if I get a 250w HPS? it doesn't have a glass shield, and the ballast in built in - but its only 250w. I was thinking of getting the home depot fan on it, then ducting it out to the bathroom fan.
On the home depot site, it says free air movement ++ boosted movement is 160cfm. would that make any difference or is that just a scam? Could it possibly work for a 250w HPS this grow, and then for the next grow - I could get a really nice inline fan and get 400/600 HPS and use the 250 for vegging?

Also I figured out a new problem for my bathroom fan exhaust I created in such a blind rush. All this hot moist air going up into the crawl space of an apartment.. mold, smell, problems. I spent hours and days on this idea.. but I think I need to get it out of the ceiling and patch up the ceiling with some panda film or something for now. Until I repair it with drywall. I think I need to mount the fan a little bit more down, in the air, and to the left. I plan on making a hole into the left side of the wall, where there should be a closet on the other side and a bathroom infront of that. I plan on pushing it into another part of the apartment, so the smell would stay inside - not up and the neighbors ceiling hahah. Now there may be 2 options.. either the new hole will just come out of the closet, or there will be more of this mineral wool insulation. If it's the wool, I'll go to the other side and make another hole, pull out all the wool, put the ducting there, and attach it to my 3' exhaust on the fan I got.

Let me know your thoughts guys.. I will be rethinking everything at work too. I just woke up and thought to throw some ideas out there.



One last edit before work - I did some measuring. I think there is about 4 1/2 inches of space between the side of my closet and the closet on the other side. Uploaded a quick picture too. Sorry for the bad drawing.. best I could do hahah

The only problem with the built in ballasts is heat. Instead of having a remote ballast where you can keep it outside the grow room, the built in ballast will introduce even more heat into the grow room. Couple that with the heat from the 250W HPS and it's going to be HOT.

You can buy the Home Depot duct fan, but you will only be disappointed. Im trying to save you some money in the long run

I vent into my attic, but because there not much humidity up there I dont have any worries about mold.

Yeah man, I understand. I would love to go with an inline fan in the beginning too.. I hate to get all this cheap shit, but I just have no money right now.. I dont know.. maybe just run the A/C for a few weeks until I can get a good inline..

For the 250w, would you suggest an aircooled/glass shield 400w HPS w/ remote ballast over the 250w since its not glass shielded/cooled/ and built-in ballast?
Would temperatures with the 400 aircooled be lower?

And for venting to the attic, how though? Isn't all the hot air going into that attic? Wouldn't that cause a lot of humidity? I'm wondering about this because of mine.. but either way.. I don't think I can do that because of the smell.. damn!

seems like you're between a rock and hard place mostly because of available funds. if you had no money limitations at all i would be urging you to get a 400 watt hps light and whatever ventilation is needed to cool it, which would give you a very healthy 7,000 lumens per square foot for flowering as many plants as you can fit in the area.

given your limitations, another approach is to shrink your grow area to fit your two plants and available light. cut the space in half again, add something inexpensive for reflectivity, emergency blankets are great for this if you can't buy a roll of mylar. if you buy the 250 watt light it will give you about 7,000 lumens per square foot in your reduced area without the cfl's.

also, since you've already shelled out the bucks for a portable a/c at 1200 watts it's only going to cost you about $1.50 a day to run, much cheaper than buying a fan. vent the a/c exhaust all the way through the ceiling and you should be ok on temps.

I would consider a T5 fixture. They will only raise the room temps about 7 deg. That's my experience I use them. In the future you can go with a veg and flower set up.