Solder Fume Fan

Here is a Solder Fume Fan with a carbon filter.
The model itself was designed in Solidworks '17. I cut a carbon filter to size from a pet store cat box filter.
The circuit itself is just 2 9v batteries run in series to get 18v and then a 10 Ohm Potentiometer. This is not ideal because the alkaline batteries are not made to run a DC fan for very long but it will work for a few hours. I suggest a better battery or using a power supply.

EDIT: After a bit of use I found that that holes in the