Aqua One 413s Sponge Padfor MariSys 240 Overflow Box.

A new 413s Blue sponge to fit the Aqua One Marisys 240 overflow box. The sponge prevents small creatures being washed out of the aquarium via the overlfow box and should be rinsed every two weeks or so. Over time the cell structure of the foam breaks down and the foam should be replaced in order to maintain good water flow.