Oh man, I've got to push back on this one a bit! I've been using Fermentology's airlock system for about two years now and I've never had a leak. Are you sure you had the gasket seated right? I know it sounds simple, but I messed that up my first time and had the same bubbling issue until I realized I didn't push the rubber ring all the way into the groove. The Kraut source brand ones are solid too, but honestly I think operator error gets blamed way too often for what's actually a decent product.