Struggling with air exchange and maintaining humidity

[myrocket]

My current grow space is a basement room 8x14x10. It has two windows which can be completely sealed, or used for ventilation. I was given a 4x4 tent which I'd like to set up and use for seedlings and to veg. Before I just had a makeshift area made with panda film and some 2x2's as a veg area.

I have the opposite end of the room (8x8 area) set up with two lights to flower.

Right now I have an 8" exhaust with a carbon filter drawing air out one of the windows. I believe it pulls air from our upstairs living area through the grow. But I don't really understand air exchange very well, so I'm not 100%. It works pretty good and I'm able to maintain ambient c02 (about 400) in the room.

I also have a 6 gallon evaporative humidifier running. It's always running at it highest speed, and it keeps humidity at almost 50%. Without it the humidity struggles to get about 27% Usually hovering around 25%.

Lastly, I have a 220v electric heater for the room which I keep set at 80 degrees.

I'd like to set up the 4x4 tent to use for seedlings/veg.

How do I get good air exchange in the big room as well as the tent? I'm concerned that if I speed up the exhaust fan in the big room, it'll draw all the humidity out.

I know I can set up an exhaust fan in the tent to draw air in from the big room, would I exhaust the tent out the other window, or back into the big room?

I apologize if this is the wrong forum.

 

[013]

The fundamentals are warm air rises & cool air sinks, so the ceiling is the warmest point in any room just like the floor is the coldest point in that same room. This works the same for room or tent whatevs. Basic principle of exhaust fan is it pulls air in from intake and pushes that same air out thru the exhaust duct.

It’s easier to draw cool air in down low passively with open vents and then suck or push the warm air out up top with fan. The vent out window deal depends are you sucking air in or blowing air out? It’s gonna do one or the other, not both.

Put layers of sheet foam down on slab then get your tent elevated up off the concrete using a wooden pallet or improvise, inside your tent use plant risers to further increase the distance above the concrete. The concrete on an indoor slab stays at 55 degrees all year long - this will give your plants cold feet, when the root zone is cold - the plants grow slowly

more will stop in later hopefully with their input

 

[Mustang92]

are you setting up 4x4 tent inside room that is 50% humidity already? can't you just control room tent is going in and combine exhaust of room and tent with t-connection and suck room air through 4x4 tent vents and equalize humidity, that shouldn't effect big room because your not increasing space your just partition existing space I'm confused as hell sorry mate if in outer space with my post.

edited: exist to existing

 

[myrocket]

are you setting up 4x4 tent inside room that is 50% humidity already? can't you just control room tent is going in and combine exhaust of room and tent with t-connection and suck room air through 4x4 tent vents and equalize humidity, that shouldn't effect big room because your not increasing space your just partition exist space I'm confused as hell sorry mate if in outer space with my post.

Yes, setting up the tent in the same big room.

So what you're saying is I'd just exhaust my tent's upper vent via t-connection to the big 8" exhaust? Like with a 4" inline fan? Then I'd just allow the 4" vent on the bottom of the tent to passively draw air in?

Apologies for being confusing. Old stoner here.

 

[Mustang92]

I think i confused myself mate, i got a blunt break at lunch so better

i think you could do it either or : connect tent exhaust ducting to grow room exhaust ducking(what) and use one fan if you think it could handling pulling the extra ducting and tent air so all exhuast is out of room OR like you said exhaust into grow room from tent with another fan. there may even be chance the smaller tent ends up higher humidity than your 50% in room with plants in it or bucket of water because your pulling from room with passive vent in tent at 50% already and moving to smaller tent/area to control ( maybe 60% in tent, 50% in room). I'd be tempted to exhaust both outside but exhausting tent in room you may even be able to use tent to mess with humidity in room a little more.

I'm assuming your in snow area with humidity as low as 25%

 

[myrocket]

I think i confused myself mate, i got a blunt break at lunch so better

i think you could do it either or : connect tent exhaust ducting to grow room exhaust ducking(what) and use one fan if you think it could handling pulling the extra ducting and tent air so all exhuast is out of room OR like you said exhaust into grow room from tent with another fan. there may even be chance the smaller tent ends up higher humidity than your 50% in room with plants in it or bucket of water because your pulling from room with passive vent in tent at 50% already and moving to smaller tent/area to control ( maybe 60% in tent, 50% in room). I'd be tempted to exhaust both outside but exhausting tent in room you may even be able to use tent to mess with humidity in room a little more.

I'm assuming your in snow area with humidity as low as 25%

Yes, Cold, snowy and very dry.

I think I'll go with exhausting both outside. The 8" fan is a cheap metal China made units. It says 740CFM. I think it's Vivosun. Adding a small 4 or 6" fan directly at the upper exhaust port of the tent to make sure I have more than enough?

 

[Mustang92]

you may drop room slightly with two exhaust fans taking air from room, you may need too control fan speeds.

 

[myrocket]

you may drop room slightly with two exhaust fans taking air from room, you may need too control fan speeds.

Good times,

And thank you for the help. Much appreciated.

 

[SmokingWings]

Right now I have an 8" exhaust with a carbon filter drawing air out one of the windows. I believe it pulls air from our upstairs living area through the grow. But I don't really understand air exchange very well, so I'm not 100%. It works pretty good and I'm able to maintain ambient c02 (about 400) in the room.

I figure it this way and the ideas are based on it being winter. The air is going out the window. It has already been warmed up by the furnace and has already had some humidity added by your humidifier. So the air does have to be replaced and it comes from the rest of the living area in the house. If the air in the rest of the house has not reached the humidity you want then the humidifier keeps running. If it is winter where you are at then the furnace has to run more often to warm it up since the air in the living area upstairs has to be replaced. Most likely it get replaced by outside air which comes in through little openings around windows, doors, electrical outlets on outside walls and even around the access doors to any unheated attic space or storage area.

It is a vicious cycle. Suck in cold dry air from outside. Heat it up and then add the humidity and send it back out the window.

Why not just have the fan or blower move the air through the charcoal filter. That will eliminate most, if not all, of the odors that you and your family might find objectionable and yet keep the warm and moist air in the room and in the tent. No need to push the air outside unless it gets to hot in the room.

Just switch the ideas around if it is summer time instead of winter time.

Several people on this message board do heating and air conditioning work for a living and will be able to explain it better. Or do a search on furnace and air conditioning and HVAC info.

 

[myrocket]

I figure it this way and the ideas are based on it being winter. The air is going out the window. It has already been warmed up by the furnace and has already had some humidity added by your humidifier. So the air does have to be replaced and it comes from the rest of the living area in the house. If the air in the rest of the house has not reached the humidity you want then the humidifier keeps running. If it is winter where you are at then the furnace has to run more often to warm it up since the air in the living area upstairs has to be replaced. Most likely it get replaced by outside air which comes in through little openings around windows, doors, electrical outlets on outside walls and even around the access doors to any unheated attic space or storage area.

It is a vicious cycle. Suck in cold dry air from outside. Heat it up and then add the humidity and send it back out the window.

Why not just have the fan or blower move the air through the charcoal filter. That will eliminate most, if not all, of the odors that you and your family might find objectionable and yet keep the warm and moist air in the room and in the tent. No need to push the air outside unless it gets to hot in the room.

Just switch the ideas around if it is summer time instead of winter time.

Several people on this message board do heating and air conditioning work for a living and will be able to explain it better. Or do a search on furnace and air conditioning and HVAC info.

If I just use a carbon filter to scrub the air in the room, and have fans in the room moving air all around... How do I maintain c02? For the last year and a half, the only way I could keep room C02 above 400 was by running that exhaust. The carbon filter was just there to help with the odor blowing out the window.

I don't like the vicious cycle for sure. They seem to suck up a lot of C02, especially when they get big and everything is chugging along.

Could I exhaust the grow room back into the living area above? That sounds difficult anyhow.

Mind blown

 

[SmokingWings]

If I just use a carbon filter to scrub the air in the room, and have fans in the room moving air all around... How do I maintain c02? For the last year and a half, the only way I could keep room C02 above 400 was by running that exhaust. The carbon filter was just there to help with the odor blowing out the window.

I have seen CO2 generators. While buying one of those might cost money it might be cheaper than running the furnace and humidifier as often as you probably already are. In the summer the air conditioner is going to be running to cool off the new air that is coming in the replace the air going out the window.

I thought that there was a seperate sub-forum on heating and cooling but did not find one. I did find a sub-forum on using CO2 but it was for processing. However, someone did ask a question there which might be of help. Here is the link to that thread. It is long but I recommend that you check out the whole thread. Sometimes they get off topic a bit but then someone jumps in with something new. Plus some of the people that participated in the thread are still around.

Clickable link:>>>>
https://www.420magazine.com/community/threads/need-info-on-using-co2-in-grow-room.463857/

 

[myrocket]

I have seen CO2 generators. While buying one of those might cost money it might be cheaper than running the furnace and humidifier as often as you probably already are. In the summer the air conditioner is going to be running to cool off the new air that is coming in the replace the air going out the window.

I thought that there was a seperate sub-forum on heating and cooling but did not find one. I did find a sub-forum on using CO2 but it was for processing. However, someone did ask a question there which might be of help. Here is the link to that thread. It is long but I recommend that you check out the whole thread. Sometimes they get off topic a bit but then someone jumps in with something new. Plus some of the people that participated in the thread are still around.

Clickable link:>>>>
https://www.420magazine.com/community/threads/need-info-on-using-co2-in-grow-room.463857/

I've had a 4 burner generator in my amazon wish list for a year. Also.... I have a CO2 controller, regulator and 20 pound tank. I think I've even looked at the thread you shared.

I would have to pay someone to run gas from just outside that room, into the room, and to install the generator. I think that's beyond what I would try on my own.

This is what I got from the co2 calculator, and why I never got the bottle filled.

This was to get the room up to 1100ppm

CO2 Calculator​

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Result
Grow room area: 1040 cubic feet
Amount of CO2 required: 1.1 cubic feet
On time: 13.7 minutes
At this flow rate:
If you are using a 20 pound CO2 bottle with a regulator, it will last 35 hours.
If you have a CO2 Generator a 5 gallon propane tank will last 108 hours.