Controlling odor in basement venting in the grow room.

I've always grown in hot climates (think like Carolinas) and even in mild winters I always vented out. Controlled the smell and the negative pressure on the grow room kept all smells in there expect day of harvest basically.

Well now I live in a cold northern city for the past few years and I kept my old habits venting outside from my basement but I am sick of throwing all that heat outside. So this winter I am thinking of venting back into the basement which has 3 tents in it.

I also know that my air-control is not the best. I got those three tents in a row, the far left actively vents to the right and so on till the far right tent takes in the air through a filter before heading back to the left through 3 tents and 3 cool-hoods before exhausting outside.

Concerns
1) with a charcoal filter I can still smell weed outside near my exhaust within 9 feet before the wind mixes enough to make it unnoticeable. Guy few houses down does a much worse job so I feel safe, however, if I were to vent into my home I am concerned that the smell would eventually build up.
2) Without the negative pressure in the basement all smells would come up, like when I am smoking joints etc and I just don't want that to happen because of kids and guests.

Solution?
1) Wondering if I added another fan with another charcoal filter just as a scrubbing unit if it would cut the cake.
2) Maybe I would be better off adding the extra fan at the end of the three tents on the outside pushing through the filter.

I don't vent since I run with AC and CO2, I just have one short vent cycle when the lights go off to purge ethylene gas.

I use carbon filters as scrubbers. Simply recirculating room air. So I can't even smell the weed standing in the flowering room. Without the filters it's strong at the curb outside lol.

Use quality filters, Phat or Phresh is all I will use have these going for nearly 7 years and they still work!

My scrubbers (two per flowering room) are 48 inch phat filters with 12 inch flanges, 12 inch vortex 1140 CFM fans and an adjustable elbow to aim the air flow. Stand the filter in the corner of the room and install the fan on top and use the adjustable 12 inch elbow to direct airflow. I use the airflow to circulate the room air so I need less fans, shooting it under the lights and above the canopy to remove the heat from my HPS lights.

If you have enough CFM why not try...
1 filter inside each tent coming to a duct cross (a 3 way-wye would be better if you can find/make one out of fittings) outside that has main fan on it with another filter on the exhaust?(main collector basically)

That gives each tent a scrub before removal and a final one before it re-enters the basement?

So...
Tent+filter. Tent+filter. Tent+filter.

3 lines into 4 way cross.(3 way-wye)

Main fan on cross with another filter on exhaust into room.

Filters+cross around $250ish?

With enough negative pressure it would semi-scrub your joint smell out of the room eventually too.

I think I will try the scrubber with a good phat filter. I started with phat filters way back but when I came to America 4 years back I started using what was on amazon mid price range, a little less then phat and they aren't as good. So around $250 get a good fan and filter to scrub. Once I am no longer exhausting out that can be used as another source to direct warm air around the basement. 2 tents on during the night and 1 on during the day and see if I can't lower my heating cost. up to $600 a month last year. Thanks for the replies guys.

I had a smelly basement before i started venting outdoors.
Even with a large single filter, enough odor escaped over the day to make it obvious and piss off the lady.
Maybe two filters, one in the tent and another on the outtake would make it better but venting outside is easiest and the smell isnt noticeable coming out the vent. My neighbors dont smell shit.

I think it is my filter but I am pulling air through a filter then going through 2 tents and I am not sure if it sucks a little air from those flowering tents through the cracks in the cold hood where the glass shield is or if its the filter. Perhaps my best choice is to add another filter and exhaust but set it low low low. Just enough to create the negative pressure but still keep some of the heat in. Right now I am blowing like 440cfm out the window.

DaFreak said:

I think it is my filter but I am pulling air through a filter then going through 2 tents and I am not sure if it sucks a little air from those flowering tents through the cracks in the cold hood where the glass shield is or if its the filter. Perhaps my best choice is to add another filter and exhaust but set it low low low. Just enough to create the negative pressure but still keep some of the heat in. Right now I am blowing like 440cfm out the window.

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You could use some or all of that warm air to heat your home and save money on the heating bill that way.

With my grow I don't have to run the furnace unless it's below 0F and windy outside. I basically have radiant floor heating. It sucks on the AC bill in the summer tho but whadda ya gonna do?