Yes, you can! If you add the peel of fresh fruit to the water kefir, make sure that it is of organic quality. Pesticides, preservatives and other additives damage the culture by weakening or killing the microorganisms.
Fruit juices are also suitable pure or diluted. You can also add other aromatic ingredients, such as a few slices of fresh ginger, a sprig of mint or similar. Instead of water, you can also use cooled tea to create even more interesting flavours. However, avoid small ingredients that are difficult to separate from the crystals later, such as lavender flowers or similar.
If you are using fresh fruit for secondary fermentation, it is best to take it out after 24-48 hours.