I've been using barrels for years and don't recall the problem in the
past, at least not as much as it's become in the past few years. I've
been getting a lot of mould around the bung in my two barrels and it
develops between weekly top ups. I generally wrap a paper towel soaked
in sulfite around the bung but even that does not seem to work.

My main concern is that it requires some careful clean up both before
and after removing the bung each time I top up.

Any suggestions.

Glen Duff