Charcoal

I used the full 28 Oz of Charcoal. Add one more layer of batting on top and add a layer of universal washable filter material on top of this.

If you have or are using some other type of filter material, the general idea is to gradually get finer as you go down in the bucket. Coarse rags or cloth could be used as filter material if that were all that was available. From time to time check the air flow to make sure you can feel a decent amount of air coming out of the holes at the bottom. Use a coarseness of the filter material to insure a good air flow. The fan may heat up if air flow is limited too much. If you want to use fine filter material then find a fan that pulls a good pressure drop.

Offered by Mike.