You can keep Java moss clean by regularly rinsing it under running water. Due to dirt and debris accumulation, you should clean your Java moss once or twice a month.
The waste that accumulates on Java moss can affect the tank’s water quality if not taken care of, so it’s highly recommended to clean the moss regularly.
If the moss is attached to a rock or driftwood, you can rinse them along with the moss until all the debris is cleared. If the moss is attached to gravel, vacuuming the stone when you do a water change is recommended.