Bad carbon scrubber?

Hi! I have a small grow tent in a 30m2 room. The air from the tent is sent directly to the room, I don’t have another option at the moment. The problem is, no matter what filter I try (I tried 4 different ones) the air quickly gets stinky. And not just in a “hmm, what’s that smell?” kind of way, it smells! I always buy filters with at least slightly higher rating then the fan. Plenty of negative pressure in the tent. The setup is, first the filter, right next to it the fan, then the ducting out of the tent. I see no leaks, all connected with clamps, then some tape over that. If I connect an extra filter on the outside, the odor problem is solved, but the airflow reduced. The first three filters would rattle a bit when shaken, which, I’m told, is a sign of a bad filter. The last one you can barely, barely hear, it seems solid, but the odor is still there. Two were Prima klima, two Can air.

Is it unrealistic to expect no odors at all in a setup like this? Is there someone here with a similar setup and no odors at all?

How big a fan and filter are you running?

I run a 210m3/h(120CFM) fan, the first two filters were rated at max 360m3 / recommended 240m3, and the last filter I bought just yesterday is rated at 480m3, a Can-Lite 425S. I did mount it outside the tent, though, just to try it. It should still work, right? I have about 2 weeks to go and the place is seriously crowded, making it difficult to do anything major in the tent. So, I connected the Can-Lite, disconnected the inner filter and the place still stinks.

Depending on the strain the smell can not be completely hidden.

You need negative pressure in the room the grow tent is located in. Do you have a exhaust going out side? Even just a bathroom exhaust fan of 70 CFM will do the trick.

But keep in mind the smell will noticeable at exhaust port so locate it where no one can follow their nose to.

Ah, ok. So carbon scrubbers don't always completely remove all the smell, I guess that's the case here. There is an exhaust in the room but I can't mount any ducting to it. For about 10h a day there isn't any ventilation in the room. Anyway, thank you!

Simpex said:

Ah, ok. So carbon scrubbers don't always completely remove all the smell, I guess that's the case here. There is an exhaust in the room but I can't mount any ducting to it. For about 10h a day there isn't any ventilation in the room. Anyway, thank you!

Click to expand...

I dont agree with that statement. Carbon filters should clean the air always. I’m in the same situation, i vent into a 15m2 room and run a 660m3 carbon filter in a 4x4. Cleans the whole house of any smells. Cooking, smoking and growing. Last one lasted almost 12 months and 3 small (1 plant) to medium (4 plants) sized grows. Zero smell.
What is your humidity? Very humid environments could cause problems with carbon filter. Do you use a humdifier?
I know you said no leaks but i would triple check it.

Simpex said:

Ah, ok. So carbon scrubbers don't always completely remove all the smell, I guess that's the case here. There is an exhaust in the room but I can't mount any ducting to it. For about 10h a day there isn't any ventilation in the room. Anyway, thank you!

Click to expand...

If your pulling air through the filter properly there should be zero smell. Create negative pressure in the tent or room and the smell has nowhere to go but the filter. The fact that you don’t have ducting results if your inability to create negative pressure resulting in more of a positive pressure situation. When you have positive pressure in a space it’ll push the smell out of the room. I’ve had a filter in one room for over 2 years and still works perfect. So if it’s done correctly they’ll last just fine.

There’s negative presure in the tent, the thing is no matter what single filter I use, I can smell the exhaust from the ducting that comes out of the tent. I have negative pressure in the room as well, but only when the main ventilation, that I have no control of, is on. When it’s off the place smells. That’s why I’d like to know if people with a similar situation have any problems with odor control. The humidity should be ok, it’s at about 45% right now. I’ll try to switch the filter tomorrow and change the ducting while I’m at it, just to be sure.

@crimsonecho What filter are you using?

I’m using a can-lite. No smells whatsoever.

Put your filter hanging up in the tent. attach ducting to it and then path the ducting outside the tent. Put your fan attached to the ducting. Make sure the air is blowing away from the tent not pushing air into the filter.

Put a piece of tissue paper/ toilet paper next to the passive vents in your tent. If the paper is held to the vent, then you have negative pressure. If it falls, you dont. If it falls, simply close the passive vents until it stays held. Even if it means just closing part of the vent not all the way, it can make the difference.

All the smell should be taken care of. You shouldn't smell anything coming out of the ducting/ air being pushed into the room from the tent (except maybe very faintly, if at all)

Something is not right, I scrub an 8x12 room full of flowering plants with a 440 cfm fan and a 6" Dura-lite carbon filter.

Simpex said:

There’s negative presure in the tent, the thing is no matter what single filter I use, I can smell the exhaust from the ducting that comes out of the tent. I have negative pressure in the room as well, but only when the main ventilation, that I have no control of, is on. When it’s off the place smells. That’s why I’d like to know if people with a similar situation have any problems with odor control. The humidity should be ok, it’s at about 45% right now. I’ll try to switch the filter tomorrow and change the ducting while I’m at it, just to be sure.

@crimsonecho What filter are you using?

Click to expand...

I use the htg specials with no issue like jarvlid said something isn’t right. I’d like to see how your setup. Plus are the sides of your tent sucked in?

Must be a bad filter or improper air flow.

The air needs to "shear" as it travels thru your filter, Looks like you need to up the cfm of your fan.
Can Fan recommends a min of 150cfm.

http://www.canfilters.nl/english/lite425.html

Iso-Max 150/410 (3), Iso-Max 160/430 (3), Max-Fan 150/425 (3), Max-Fan 160/430 (3), Can-Fan RK 150/470, Can-Fan RK 160/460, Can-Fan RKW 150/460, Can-Fan RKW 160/460, Can-Fan RK 150S/460, Can-Fan RK 160S/460, Can-Fan RS 150/470, Can-Fan RS 160/450

Ok, so looks like it really was an error on my part with the last filter. The first ones were bad, carbon was loose and I opened one and saw pellet carbon, which they say isn’t any good.

Previous setups were always filter and next to it the fan, blowing air out through ducting that had a 90 degree turn as I have to run the ducting through the ceiling of the tent, no space on the sides. Now there’s only the filter in the tent, the fan is outside, attached to the ducting and that improves airflow. It’s noisier, but not too loud. So far there’s no smell. Thank you all!

"They" can say pellets aren't any good but they would be wrong. Been using them for 2 years. But, im moving 400cfm over 20+ lbs of pellet carbon in my diy scrubber. I change it every 6 mos, but it would prob be good for 8-10.

Simpex said:

Ok, so looks like it really was an error on my part with the last filter. The first ones were bad, carbon was loose and I opened one and saw pellet carbon, which they say isn’t any good.

Previous setups were always filter and next to it the fan, blowing air out through ducting that had a 90 degree turn as I have to run the ducting through the ceiling of the tent, no space on the sides. Now there’s only the filter in the tent, the fan is outside, attached to the ducting and that improves airflow. It’s noisier, but not too loud. So far there’s no smell. Thank you all!

Click to expand...

Fans are always more efficient pulling rather than pushing. Also filter your intakes, running negative pressure can draw mites, thrips etc.. into your grow.

Doesn't a fan push on one side and pull on the other?

1212ham said:

Doesn't a fan push on one side and pull on the other?

Click to expand...

Yes, that's why it's important to place the restriction on the right end.

Why would restricting the low pressure side give higher efficiency?