QANVEE Sponge Filter / Sponge Replacements (YX-300 / YX-600)

QANVEE Sponge Filter / Sponge Replacements (YX-300 / YX-600) Ultra-thin design, saving in-cylinder space. Both mechanical and biological filtering functions Comes with tiny spherical filtration balls for cultivating beneficial bacteria. Perfect replacement for air stones, in small and simple setups. Works great for fry tanks Comes in 2 sizes. YX-300 / YX-600