Questions about pushing exhaust

[Laserawesome88]

Hi everyone! I’m new around here, about a month into my first grow (Mephisto CDLC and DBCx3BOG). I have a 2x2x4 tent (should have gone taller...) and have no room for my exhaust fan and carbon filter inside the tent, so I have both sitting on the floor outside the tent which seems to work fine so far.

I have a couple questions that I’m hoping an experienced grower can advise me on:

1. Should I use the pre-filter on the outside the carbon filter or just leave it off entirely? Or should I put the pre-filter INSIDE the carbon filter?

2. Does anyone use a filter at the exhaust duct inside the tent as a prefilter to replace the traditional prefilter? If so can you point me towards a good one?

Thanks for any advice! I tried researching this and haven’t found much beyond the fact that pushing exhaust to a carbon filter outside the tent does work.

 

[Son of Hobbes]

Hey welcome to the Autoflower Network! Great to have you here!

1. Should I use the pre-filter on the outside the carbon filter or just leave it off entirely? Or should I put the pre-filter INSIDE the carbon filter?

ALWAYS use the pre-filter. The pre-filter is catching large micron particles like dirt and dust, trapping them in the filter. It's the smaller particles that tend to contain the VOC's (volatile organic compounds, ie evaporated terpenes,) and without the filter the carbon inside gets coated faster with the things you don't actually want filtered.

Pre-filters do get dirty over time, I'd suggest pull the filter after every grow and either hand washing/rinsing it, or put a mild detergent in the wash on delicate and air dry it.

Run them on the outside of the filter if you're pulling air THROUGH the filter (which is what I highly recommend, seldom should you ever push air into the filter, but sometimes people run the scrubber outside the tent because of space limitations, etc. Not ideal, can be done, just food for thought.

2. Does anyone use a filter at the exhaust duct inside the tent as a prefilter to replace the traditional prefilter? If so can you point me towards a good one?

You can find 6 inch and 4 inch in-line filters that are basically mesh screens that cap the end of the exhaust line. I've seen them marketed as "bazooka filters." Not necessary, but it's an extra step in catching any crap you don't want in/out of the area.

 

[Laserawesome88]

Thank you! It looks like I will need to run the scrubber outside of the tent so I will look for those “bazooka filters”.

 

[Laserawesome88]

For anyone else reading this who has the same issue, this is the product I finally settled on to keep dust, bugs etc out of my fan while pushing exhaust: GrowBright Double Layer 4 Inch Duct Filter

I looked at bazooka filters but they ended up being nearly as big as the carbon filter itself which will not fit in a 2x2x4 with lights etc. The product posted above is almost flat and covers the duct with a screen and flat carbon filter.