Scrubbing inside of a room..

So if you scrub the air inside the room, what would the general rule of thumb be? Ex if I have a 6” fan pulling 400cfm out of the room with a CF.. what size filter/fan combo would be needed inside the room to prescrub as secondary measure? Would a 4 inch work?

Ideally you would want a 6" filter but technically you could put an adapter on and use a 4", you're losing efficiency and overall scrubbing capacity.

You shouldnt need to scrub. If you can still smell anything coming from your exhaust either your filter is spent or you're not achieving any negative pressure and odors are migrating out of the grow space.

Not my current situation just been seeing posts about people scrubbing inside of their rooms as well and I wasn’t sure how that worked.
I’m guessing you’d need to exchange the air almost as much as your exhaust setup?

BigGreenThumb said:

Not my current situation just been seeing posts about people scrubbing inside of their rooms as well and I wasn’t sure how that worked.
I’m guessing you’d need to exchange the air almost as much as your exhaust setup?

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Scrubbing is not very effective. Odor is constantly being produce so you can never really eliminate it entirely. To be honest Ive never read or heard of any rule of thumbs or guidelines. The more plants in the room, the larger the scrubber seems logical to me.

I run my stand-alone scrubber as slow as possible. Start high, then reduce to sweet spot. Running the fan full throttle is annoying and in many cases excessive. I've read that carbon filters work better at lower cfms.

More air exchange does require more scrubbing. Admit i dunno how to calc.

The wife let's me know if I need to up the fan speed. Lol

running a 20 inch phat with a 6 in on it running it at half removes all the smell once I open the tent it reeks

Scrubbing CFM vs Exhaust CFM per filter size are different.



If you want 100% control of odor at peak stench you will want to cycle the volume of the room every minute, 2 minutes and you start loosing the battle.

also @Renfro what is your view on inline carbons?

I use 6" 400cfm in 1000ft3 & I can't smell my ripening plants unless I'm within 2-3ft so I feel it works enough for me.

Thanks Renfro that answers my question! Will keep this in mind if things get stinky.. simple enough to just add a fan/scrubber in a corner If needed

Gond00s said:

also @Renfro what is your view on inline carbons?

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They are pricey. lol

What I thought

If I was considering an inline carbon filter for an exhaust that is going outside I would seriously consider a quality inline ozone generator, snap seam duct sealed with mastic. You do need a length of duct after the ozone generator to allow the ozone to mix and do the job. I prefer the corona discharge models. Lasts longer than the inline filter lol. Power it with the blower so it shuts down if the airflow stops.

Renfro said:

If I was considering an inline carbon filter for an exhaust that is going outside I would seriously consider a quality inline ozone generator, snap seam duct sealed with mastic. You do need a length of duct after the ozone generator to allow the ozone to mix and do the job. I prefer the corona discharge models. Lasts longer than the inline filter lol. Power it with the blower so it shuts down if the airflow stops.

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The coronas are nice but super pricey for the amount of ozone produced.


I used the 8in uvonair cd-800 ($500+) for a few years. The convenience of splicing it into an exhaust and the dual switch for controlling ozone output (up to 1,100mg/h) was nice but needs the extra length of duct (15ft) like you said for mixing.

When the element burnt out I opted to replace it with an amazon ozonator that produces 6,000mg/hr, cost is under $100.
https://www.amazon.com/gp/product/B00JAP7388/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

With the dial in the always on position it sits in the scrubber exhaust mixing box before being dumped outside. Can put it on a cycle stat to turn on for x minutes every x, or on the same leg as the blower as you said so it doesn't run if your exhaust stops.

dakindgrind said:

The coronas are nice but super pricey for the amount of ozone produced.

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I just like not having to check the bulbs lol. I have a Uvonair CD-1200 that I ran for a few years before I got AC units. It worked like a champ, still there if I need to run the exhaust line for whatever reason. It has the high / low switch, never needed high. I think on high it's like 90 watts.