ventilation question...

So im going to do a semi sealed room, 9x5x7. I will ducting from outside the room to the hoods and then out through a window to cool a pair of 1000s. Ill have 12h btu window a/c to cool the room. Ill run a carbon filter/fan not to exhasut heat or smell, but just to constantly scrub the smell and itll help circulate air.

That leaves the problem of bringing in fresh air. I was thinking to pipe it in with an inline fan and to exhaust with another inline fan (not through the filter) that would both turn on and off periodically together.

So my question is...how often should on/off intervals be? Pipe in air and exhaust it for 5/10 mins every hour? Is that enough? More? At 120 cfm in and out i could completely swap all the air out in about 3 or 4 mins. But how fast would 6 to 8 plants deplete the co2 in that fresh air?

Surely i am not the only one doing it this way?

I didnt read you had co2 ...so you have a co2 setup?

The 120 cfm fans for intake and exhaust should be running 24hrs in that space. Id test it and see but there are some factors like summer is coming and its going to get hot in there...

Diabolical666 said:

I didnt read you had co2 ...so you have a co2 setup?

Click to expand...

No, no co2. Im not there yet. But 8 am setting up for it a grow or two down the road. Ill want a mini split for that which i cant afford right now.

Im not worried about heat. I have that all sorted out, as above.

I just need to know how often to exchange the air in the room if i am piping in fresh air is all.

I tbe past i would pipe it in and exhaust it the whole time the lights were on. That creates a couple problems where i am at. It is hard to build the right humidity during lights on (i am in a very dry region) and, during winter, the air is too cold (drops down to -30 often). Even so, the problems are manageable...just not ideal. I think i can do better.

So...my solution is to just pipe it fresh air once ot twice an hour and exhaust it, as the co2 in that fresh is depleted by the plants. That will allow my humidifier to build and maintain humidity (instead of it all being sucked out constantly), which is my biggest problem right now.

Don't force air into your room with an inline. Just pipe it in and let your exhaust fan and filter pull the fresh air into your room and don't use the same size pipe as your exhaust go an inch smaller if possible.

Atomic strains said:

Don't force air into your room with an inline. Just pipe it in and let your exhaust fan and filter pull the fresh air into your room and don't use the same size pipe as your exhaust go an inch smaller if possible.

Click to expand...

A smaller intake size to create a little nevative pressure?

you could use your intake into the room, hook up a filter then pull air thru that, the lights, and out. Its not as great at cooling as your set up now, but it will create better exchange of air. Your filter doesn't need to be on the system its on now since that air doesn't touch the goods, If you made small intake hole and push air out of the tent into window or room thru that same filter, you would exchange that air, as a separate system from your light cooling.
Not sure about your set up conditions etc but I recently had to make choices between the two, and had to choose option A to not create new vent holes in windows etc
Good luck!

I'd run an extra fan just to vent the room. Maybe use the carbon filter fan to vent. That way the air won't smell like skunk's ass. Figure out the cubic feet of your room. Width x Height x Length= Cubic feet. Now let's say you have a 10x10x10 room, that would be 1000 CF. If you ran a 400cfm fan for 3 minutes it would completely vent the room. The thing is you never get 400cfm at the output. The fan may put out 400cfm but when you factor in hose length, elbows, etc... it will always be less than that. So the truth is you really need to run the fan at least twice as long as you think.

If you have a big room without many plants you don't need to vent as often. Three times during the light cycle and maybe a couple during the dark should work fine. I set my vent fan to come on for 15 minutes every three hours and don't fuck with it. If you run A/C and have a big room you may decide to vent just once a light cycle.

find the volume, then multiply it by however many air exchangs you want in an hour and divide the total by 60 to figure how many cfms you need. easch elbow at 90 degrees is equivlant of taking away one 5 foot piece of straight pipe and the flex you use to pipe it in has really bad friction and dynamic loss. but for the size of your area if it was me i would hook up some flex to a filter run it through your light and out of your room, make a small hole located in a bottom area of your room to draw the air dont force air in justr let your exhaust pull it. the negative pressure will cut down on smell. also just take your other fan and put it in theere blowing on your girls and help keep the humidity down. hope that helps

Thanks....but i am up to speed on all that.

What i need to know, still, is how often do i need to exchange the air in the room? Or...how fast will 6 to 8 plants use up the co2 from the fresh air brought into the room?

they will be good dude, you will have a constant air flow at all times so it wont deplete. you said your fan was 400 cfmÉ if so just hook it up and let it run, it doesnmt hurt to leave that on all the time. more air exchanges the better really. when it comes to venting there isnt much to iut other than making sure your pipe isnt saging and you use minimal elbows. and for co2 like i said just leave your fan on and let it pull air. you can also add co2 to your room as well. ive never done it because i just use natural ventilation

Actually.... I have tried it the way youre saying and it doesnt work for me...for stated reasons. So i want to go semi-sealed and bring in fresh air periodically...

StinkBud said:

I'd run an extra fan just to vent the room. Maybe use the carbon filter fan to vent. That way the air won't smell like skunk's ass. Figure out the cubic feet of your room. Width x Height x Length= Cubic feet. Now let's say you have a 10x10x10 room, that would be 1000 CF. If you ran a 400cfm fan for 3 minutes it would completely vent the room. The thing is you never get 400cfm at the output. The fan may put out 400cfm but when you factor in hose length, elbows, etc... it will always be less than that. So the truth is you really need to run the fan at least twice as long as you think.

If you have a big room without many plants you don't need to vent as often. Three times during the light cycle and maybe a couple during the dark should work fine. I set my vent fan to come on for 15 minutes every three hours and don't fuck with it. If you run A/C and have a big room you may decide to vent just once a light cycle.

Click to expand...

So you bring in fresh air for 15 mins every 3 hours? And that is good without using co2 to suppliment?

don't ya just wish we could all just have the legal ability to have a lil greenhouse tent with airflow? Or am I just s dreamer?