I have a filter on the line going into the jug, then I filter again as it goes into the tank. I also have a filter in the fuel line when the plane is running. I know this may sound a bit extreme, but it really is not. I had a bunch of clogging problems with my plane when I did not have all of these measures, now I have no problems at all. Before I did this I had multiple dead sticks because the engine flamed out due to a fuel line clog, since then I have had no problems with fuel.