Rinsing a SCOBY is generally not recommended, as it can disrupt the delicate balance of bacteria and yeast and potentially introduce unwanted microorganisms. However, gently peeling off excess yeast buildup is acceptable.
The SCOBY (Symbiotic Culture Of Bacteria and Yeast) is a complex ecosystem. Washing it with tap water can introduce chlorine and other chemicals that harm the beneficial bacteria and yeast. While a healthy SCOBY can usually recover, repeated washing weakens it over time. Instead of washing, focus on maintaining a clean brewing environment. If you notice excessive yeast buildup (the stringy brown bits), you can gently peel off a layer or two. This removes the excess yeast without disturbing the core culture. Ensure your hands are clean before handling the SCOBY. A healthy SCOBY will naturally maintain a balance, and excessive cleaning is usually unnecessary. A small amount of yeast is normal and even beneficial for fermentation.
If you're concerned about the appearance of your SCOBY, consider using a SCOBY hotel. This is a jar filled with starter tea where you can store extra SCOBYs. This allows you to rotate SCOBYs and keep a backup in case one gets damaged or contaminated.