Recently acquired a used whiskey barrel, and want to keep it swelled and free of bugs until my RIS is ready to rack over. I filled it with a citric acid and potassium metabisulfite solution (in which I wish people would have emphasized strongly makes toxic gas when dissolved in hot water). For those who have not done this yet, make sure you make the solution outside while wearing safety gear, and not like my idiot-self inside with nothing on.
Problem is I do not have a bung. I am thinking of capping with aluminum foil and saran wrap.
Will aluminum and/or the saran wrap react with the solution? Is there a better option?