aquapapa bio sponge filter for betta fry aquarium fish tank up to 55 gal, 3-pack (l)

The sponge will need to be rinsed every time it becomes dirty, about once every 2 to 4 weeks. It's helpful to reserve the beneficial bacteria by washing the sponge gently with water from the fish tank instead of tap water. After 3 to 6 months usage, the micro holes of sponge is gradually clogged by the tiny debris, the beneficial bacteria won't have as much living space as before. That's when the sponge filter starts to lose its efficiency. So it is also recommended to replace the sponge once every three to six month or when the sponge gets worn out.