Carbon Filter no longer controlling odor in tent

Hey everyone,

I have a 4x4 tent with a 400 CFM exhaust and passive intake.
The carbon filter I'm using is a Phresh 6" x 16" 400 CFM

The air flow is:

Carbon Filter --> Sealed Reflector --> Fan
Carbon filter is in the tent obviously and fan is outside the tent.

Carbon filter has been in use 24 hours a day for exactly 74 days.

Odor control was 100% up until about 2 weeks ago. Over the last 2 weeks, I have been able to smell odor in the room. 2 Weeks ago it started with a very faint smell to today where it is overwhelming...almost as if I had no filter at all.

What do you think is the most likely situation:

1) Carbon filter is no longer filtering properly. Seems unlikely based on how old it is.

2) I have developed a leak somewhere - When Lights come on I will be doing a smoke test to try and determine this.

3) The quantity and/or strains of the plants I am growing simply can no longer be controlled

Any help would be greatly appreciated. I have a secondary line of defense...the room that the tent is in is reasonably air tight and I have a 750 CFM fant pulling thru a 750 CFM Phresh filter with passive intake so no odor is escaping that room. Problem is, I'm 39 days into flower and it's going to get worse. I'm going to have a real problem if the odor escapes my secondary line of defense.

4) Humidity is higher than normal

or maybe the filter can only process so much. I like to oversize my filters, and I prefer phat over phresh.



- Jiji

always go over kill on the filter, my guess is the fan is pulling the air through too quickly and not scrubbing it properly. i know you have matched the rated filter to your fan but the filter will last a lot longer if you have a less powerful fan.

never used phresh but they are a pretty big brand so should at least work, i use rhino pro and not had a problem since my first crop where i ripped a hole in the ducting
hope you get it solved asap, the nerves can take a beating when you are stinking the street up.

Jiji: Humidity is pretty consistent and fluctuates between 46% and 54%

I have a speed controller. Do you suggest reducing the speed and see if that helps? I went 400 because I expected that was more than what I would need.

I'll check for leaks 1st. Then reduce the fan speed and check in a few hours.

Generally speaking, should a properly functioning ventilation and filter system be controlling odor near 100%?

Reduce speed... U want a slow filter...also sometimes humidity will sticky the carbon... Allow some dry time.... Possibly has been overcome by product - replacement might have to be done.....i would think u should put fan on heat switch so its only used to drop from 79* down to 72* then rest for a time

Update: Smoke test did not reveal any obvious leaks but with the HPS light I found it difficult to track the smoke. I'll will do a follow up test right at lights out with a flashlight and see if I can confirm.

I reduced fan speed to approximately 70%. I'll monitor any potential heat issues that may arise.

As to smoke test it may be easier to reset all ur connections one at a time to ensure tape is properly set...

daemon kronic said:

As to smoke test it may be easier to reset all ur connections one at a time to ensure tape is properly set...

Click to expand...

To be safe I'm going to go ahead and order a replacement filter tonight if the odor is not gone in a couple of hours and take the opportunity to either check or just redo connections like you suggested.

Thanks everyone for all of your feedback and help!

Setup a second filter in the tent running as a scrubber.

SnapsProvolone said:

Setup a second filter in the tent running as a scrubber.

Click to expand...

Yeah, I could do that.

In the 13' x 17' room that the tent is in, I actually have a 200 CFM scrubber running in addition to the 750 CFM exhaust. If the odor doesnt leave the 13' x 17' room then I'm fine.

I suspect moving the 200 CFM from the room into the tent would be much more effective though, huh...

this sounds an awfully elaborate set up for a tent grow, any pics?

ghb said:

this sounds an awfully elaborate set up for a tent grow, any pics?

Click to expand...

It's not elaborate...odor control is of critical importance, that's all. 12/12 from seed experiment in my signature is the grow in question.

Well, after reducing the fan speed the smell only got worse. I decided to order a replacement...chose 550 CFM rated filter...an increase over the 400 CFM one I currently have.
I suspect it either failed or like many of you said, became compromised due to humidity.

So i made a simple and VERY effective filter system.3 inch plastic T fitting the 2 sides with smooth openings, the top with threads..2, 3 inch drain caps,1, 3 inch Threaded cap for the top, 4 , 3 inch round pieces of window screening .. ..Home Depot......2 round carbon filters , and a bag of granulated carbon. Pet Smart... Put 1 screen and round filter and another screen in each drain cap and slide into each smooth ends.. Rinse granulated carbon and fill from the top.. Place the cap and attach 4 inch dryer duct to each end.. No smell at all..

Hot Diggity Sog said:

Well, after reducing the fan speed the smell only got worse. I decided to order a replacement...chose 550 CFM rated filter...an increase over the 400 CFM one I currently have.
I suspect it either failed or like many of you said, became compromised due to humidity.

Click to expand...

What type of fresh air intake do you have?

Potismedicine said:

What type of fresh air intake do you have?

Click to expand...

Just passive...my tent has flaps on the bottom that I open.

The room that the tent is in is in a very large basement so ultimately all of the fresh air and exhaust air just gets recirculated in a 3000 sq/ft basement.

Hot Diggity Sog said:

Just passive...my tent has flaps on the bottom that I open.

Click to expand...

Have you cleaned the prefilter at all?

I clean my prefilter after every grow because a dusty prefilter can cause smell issues due to dust blocking parts of the carbon bed etc.

I also massively over spec my filters.

250cfm fan - 500cfm filter using RhinoPro like GHB.




J

jondamon said:

Have you cleaned the prefilter at all?

I clean my prefilter after every grow because a dusty prefilter can cause smell issues due to dust blocking parts of the carbon bed etc.

I also massively over spec my filters.

250cfm fan - 500cfm filter using RhinoPro like GHB.

J

Click to expand...

I have not but I'll go ahead and try that. It does not look dirty but I I'll clean it anyway. Do you just hand wash it and let it air dry?

Hot Diggity Sog said:

I have not but I'll go ahead and try that. It does not look dirty but I I'll clean it anyway. Do you just hand wash it and let it air dry?

Click to expand...

Yeah hand wash, rinse it until water is clear then allow to dry naturally.

If you force dry it, it will end up fitting a barbie doll as a dress lol.


J