Reasonably well sealed grow room - closed loop carbon filtration?

[Bluey]

I have a pretty well sealed grow room with excellent climate control but have to changeover the air in the room to keep CO² up to the plants. I do this by venting 5% of the air movement from my wall air-conditioner and I have another AC that runs intermittently and removes the heat by extracting the air out of the room so it sucks in fresh air through tiny air gaps in the room to do that.

Problem is the extractions and changeover produce that much stinky dank outside when in flower you can smell it from the public road on some days just driving past if you have your window down. This is not good!!

I cannot filter the extractions because of the way it's setup but I could put a carbon filter and fan inside the room just to circulate on what I guess is effectively a closed loop. So it would remove odours from the air inside the room hopefully before things get way too dank and extract the filtered air back into the room. The rooms 580 cu.ft. or 16.5m³. I have a 10" silenced variable speed fan (Max flow 1840m³/hr) and high flow 10" commercial carbon filter.

Has anyone done this or seen it in action. Is it effective? Am I wasting my time?

[YYCannabis]

I’ve been contemplating the same sort of thing. My thought is to simply use an inline duct fan with a filter on it and just leave it to run 24/7 in the garden, but i only need to worry about a 4x8 space. One thing to try to balance out would be the fan speed vs filter contact time. It’s not about pulling as much air as you can through the filter, but needs to be throttled down to make sure the stanky air is in contact with the filter material long enough to be effective.
I would think that there should be some info from the filter manufacturers website that recommends volume/speed rates for their products.

How are you measuring the CO2 levels?

[ductwizard]

hey bluey, i was an hvac mech. for 25 yrs. so here's my 2 cents. a closed loop sounds like it will work in that case but i think you would have to add to your 5% makeup air. if you add a carbon filter that would solve your outdoor stink prob. or you could add a louver to exchange air between rooms

[Bluey]

Thanks for the quick responses.

The 5% make-up air has worked fine for quite a few grows to date. I don't know how many changeovers that is per hour but I'm getting normal yields for a coco grow and make-up air has increased with the 2nd AC.

I'm not measuring CO² levels in the room. It's drawing some make-up air in from living quarters so this should be quite a bit higher than normal outside air.

I'm using a carbon filter rated at 2400m3/hr and was hoping to run the fan at around 20% capacity tops so around 370m³ or 20 odd room changeovers per hour. Hoping that's enough to kill the dank and should also make for a healthier environment for me, which I also need.

I'll only run it mid to later flower when humidity is inder 50%RH and seal the filter the rest of the time. Should last a long time that way 🤞