Can I do smaller batches than 30 L (8 US Gal) and still expect efficient heating/cooling from the GF30? Kim April 01, 2022 09:40 Updated When heating the contents of the fermenter, this will work with any amount of liquid as it heats from the bottom. Anything below 19 L (5 US Gal) for cooling won’t be as effective. Related articles Can I add fruit/other adjuncts directly to my fermenter? What happens if I crush my grain too fine? What do I do? Can I bottle directly from my GF30?