Well, the last time I messed with a mr. beer, was almost 10 years ago. As I remember, most mr. beer extracts recommend table sugar, and that takes along time to carbonate, and to my taste buds give an off flavor. We had better success using corn sugar from the local home brew shop. And those PET bottles are nearly worthless for beer. The caps on ours were leaking after one or two batches, and we just moved up to regular bottles.