Review on 🐠 Optimize your Aquarium Filtration with CNZ 50pcs Bio-Balls Filter Media for Black Fish Tanks, 1-inch (1-Pack) by Lindsay Ray

I use these for cycling new tanks. I keep a few in all my aquarium filters and when I set up a new aquarium I remove them from the existing tanks and put them in the new filters. This significantly reduces the time it takes to cycle a new tank. They stand up to the test of time very well, do not impede flow or clog the filter. They're well made and the case they come in doubles as a media case for them, although I only put them in my filters on their own.