I have heard of this..
get a 5 gallon bucket with lid. buy a fan that has the same measurement of the inside bucket diameter. that way it will fit perfectly inside. If you get a fan that has a base on it, make sure it has the motor inside the fan cage. remove the base...get the drill and put several holes around the top 1/3rd of the bucket...go to the nursery and buy SOIL MOIST. SOIL MOIST is tiny crystals that expand way big when water is added to it. Put about 10 cups of water in the bucket. Put the crystals in and let them expand. Mix some kind of odor control solution (get it at the hydro store. ) or something from the odor control section in the baby section from walmart. i was told that pinesol works. ..the fan should fit right on top of the bucket, snugly. if the fan is a tad to small for the five gallon bucket, cut a hole into the 5 gallon lid and set the fan on it. secure it down if you want....Plug it in and the fan will draw air into the holes, and out the fan to neutralize the odor.