I have a 4'x4'x8' shower in my basement that I have converted into my grow room. So far it has worked well. However when the goodies go into flower they smell the entire house up even with two odorizers that automatically go off every 9 minutes and a big carbon scrubber in the same room as the plants. What I want to do is put a zipper door on and close the room off . I have a big closet on the other side of the shower that I run the electrical and dehumidifer over to. My problem is how should I inject fresh air? My first thought was to get a 4" inline fan and some flexable duct and just blow air from the closet back into the grow room. Is there a better way? Could I put a Ionic Breeze air purifier in the room and call it good? Any ideas are appreciated.

an air purifier isn't going to replace depleted levels of C02 and Oxygen though - so you really need fresh air from another room or from outside somehow.

is there in window in the basement you can crack open for a couple of hours a day or something?

Not really, the whole point is we have family and company over regularly so I cant have hoses or anything out in the open. Because of the smell I am trying to seal off the room completely. So I need to inject the air in somehow. I get your point about the purifier though. Do you think I could hook a small air conditioner up to a inline fan with some duct hose?

Sounds like you've got yourself a really big problem.

You wanna grow weed.
But your afraid that the company you have coming over regularly will notice.
Ask yourself something first buddy, "Is it worth the risk of getting caught".

Everybody's situation is different on these boards it seems like.
I have company come over as well also, but they all know I smoke weed. So my house always smells like weed.
I grow my own weed because of one reason only, "I'm a cheap bastard".
I refuse to pay obscene prices for dirt.

Dude if you wanna grow weed efficiently but stealthy. Then you'll need to
to toss the shower idea. Sounds like a bad idea.

Try getting yourself a cabinet or use a closet in an inconspicous place in the house.

It seems to me that this problem is really not that big, if you make a zippered door air will seep in. As long as you have active exhaust the intake will take care of itself. If you wish to you can use the 4in inline duct fan to help getting air in but it is not necessary unless you have built the most amazing air tight room. I'ld just go ahead with your plans and if you start to notice a problem try to come up with a new solution then.

Bong juice, I already grow and my house smells like weed too. I just dont like having to burn a bunch of candles and/or explain my opinion on weed every time someone smells it and asks. The point is I want it to be completely stealth and the fresh air is a concern.
Regrets, this may be a stupid question but how am I going to notice if the plants are not getting the right amount of fresh air? I have always been told that fresh air is one of the most important components. Will there just be yellowing or will it stunt bud production?