Yes, you can ferment in an all-in-one brewing system! This type of brewing setup is becoming increasingly popular with home brewers. All-in-one systems are designed to allow brewers to easily brew, ferment and carbonate their beer without having multiple pieces of equipment. An all-in-one system usually consists of a fermentation vessel, a chiller or cold storage solution and a serving keg. The benefit of using this type of system is that it allows the brewer to control every aspect of the brewing process from mash temperature through to final packaging without having to invest in additional hardware or components. When using an all in one system for fermentation, there are some important considerations that need to be taken into account such as ensuring appropriate temperatures for yeast activity; controlling oxygen levels; managing off flavors; managing headspace; monitoring pressure during fermentation and conditioning phases; sizing the keg correctly for your batch size and understanding how much CO2 should be used when transferring from primary fermentation vessels into secondary or serving vessels. Ultimately though with careful attention these issues can easily be managed allowing you make delicious beer at home quickly and efficiently with minimal hassle!