I use these - available in 1.25, 2, 2.5 & 3G sizes. I drill a 1" dia hole in the top, insert a bung and airlock. You can also put them on their end & remove the spigot and use a 7.5 bung and airlock. I don't like the 3G - the ones I had cracked in the corners. BPA free, designed to hold all...