So I'm thinking of trying to make one of these. I have seen several threads on how to make them but I have a few questions. How efficient is this on reducing/completely masking the smells? I suppose I will combine the carbon filter with an ONA bucket to be sure. Another question I have is about fans. As I understand it there needs to be a fan attached to the filter AND a fan on the outside of the box both exhausting the air out of the box? What would be the best kind type of fan to use for these considering I'm in a closet box 17 in x 32 in. X 2 ft