Critique my very cheap carbon filter design.

Hey guys, noob here. Excited cause I will be starting my first grow soon! (Turning a minifridge into a growbox)

Anyway, being cheap I somewhat came up with my own idea for a simple small carbon filter, mainly inspired by This Thread.

So here's my plan:

I will start with this mesh pencil cup, it's 4.2 inches around and about 5" tall.

Next i will take a standard carbon pre filter, like this one:

Cut it to size, and wrap it around the cup, securing it with zip ties and duct tape.


Lastly I will stick my 4 inch inline fan into it (100cfm). My hope is that because it is somewhat conical the fan should fit into it nicely.

Excluding the cost of a fan, this could be the cheapest filter I've ever seen, with a total cost of under 10$.

How does it look to you guys? I guess my main questions are:
1. How many times should i wrap the carbon filter strip around it?
2. Will a 100cfm fan be able to push enough air through it to accommodate a passive intake? (My fridge is a decent size, I'd guess to be around 3-4 sq feet)

You don't want to actually put the fan inside of it. That would make it much more inefficient because you want air being pulled through on all sides of the filter, evenly. The cfm is fine, but I'm unsure if it is a good match for your filter. If it pulls the air through too quickly, it wont scrub as well. Also, you're going to want to buy activated carbon to stuff inside the actual filter itself. This will add more resistance for more thorough scrubbing and obviously filter better in general, just make sure you put a screen in it to make sure it doesn't get sucked into your fan.