Hi all

I have a grow going right now, Im a little over 3 weeks in and they look wonderful. I am growing in a modified fridge with a 175w MH, 70w HPS, 6 Daylight CFLs and 2 2700k CFLs for now.

The exhaust fan I am using is a NuTone 80CFM bathroom exhaust fan. Its a squirrelcage style blower fan with an 8 & 3/8" x 8 & 3/4" semi square inlet, and a 4" square outlet with an adapter on it to make it 4" round.

My first design was a small box frame with a carbon filter built into the middle, and it was attached to the inlet with duct tape. The inlet is not meant to have anything mountes to it, but rather a flimsy plastic piece clipped onto it. The oringinal filter worked for a while until the duct tape failed, but the temps were higher than Id like.

Now, I have a very thin filter mounted to the inlet in the same fashion, and temps are GREAT. Max temps are like 78 right now, the only problem is that I believe more air is being sucked in through the small cracks & holes that I could not seal than through the filter, so my garage is getting a little stinky.

So what I want to do is to make a filter that goes AFTER the exhaust, but that does not restrict airflow so much that it creates a negitive (or positive, whichever is bad, haha) pressure forcing air back into the fridge. I have spent a decent chunk on this setup as is with many failed designs. As of now if I can get this filter thing worked out it will be all set. I just dont want to design another one and have it fail.

I want to do a can style filter such as the one in this DIY writeup, but I cant figure out how long it needs to be, or if it will work right with my style of fan. Using his calculations I figured up that I need roughly a 4.8" long can filter for my 80CFM fan, that just seems a little short to me. If anyone could help out here that would be great. Ive done so much reading on this my head is about to explode and I feel Im not even close to a "for sure" answer.

Thanks a ton guys. If you need to see any pics of my setup I have a link in my sig for my fridge grow.
KB

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150w HPS Mini Fridge Grow (Finished 07/26/09) ---- My Fridge Grow (Finished 09/07/09)
Autoflower Thread & Resource Guide

Bump

__________________
150w HPS Mini Fridge Grow (Finished 07/26/09) ---- My Fridge Grow (Finished 09/07/09)
Autoflower Thread & Resource Guide

i say use ozone. It activly scrubs the air and if you make your own you could make one the goes right inline in the exhaust duct.

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My grow Journal before it went south After the revamp