I could not find a carbon filter smaller than 160m3. It's the smallest size but you're right that it will still block my space a bit. So what do you think about humidity? Since this filter will vacuum all the air inside, will it dry the air? Will I have a humidity problem? I have a small humidifier, I will put it next to the flower pot.
You really won't be able to control the humidity inside your cabinet. Your exhaust fan will need to be on the lowest setting. Honestly one of those ac inifity pancake cabinet exhaust fans is all you'd need.
To a degree, the plant itself will be a part of regulating humidity. The more vegetative mass inside the space, the more humidity, but it's unlikely you'll be consistently hitting 60-70% RH, but that's Ok, don't fret. IME the biggest impact you see with lower RH is decreased growth rate. Others mention it can lead to deficiencies, and I can believe that, but it hasn't been my experience. But you'll need to be on point with everything else. Proper lighting, watering, and feeding. If those are all good, you can do this successfully.
If there's a nearby window, open it up when the outside RH gets really high, like before and during a heavy rain. Get used to monitoring temps and humidity inside your cabinet, inside your house, and oudoors. It really does help to know.
The small "cool mist" humidifiers don't help. They just don't affect the RH enough to matter. You are better off with a bucket of water with a towel half in, half out evaporating as a humidifier, no joke.
