So I got a canister filter in the mail today! It will be a bit before I get it set up, as I don't have media for it yet. Well, it came with bio balls, but everything I've read about them makes it seem like they are crappy. I have tetra internal filters that I've been using like they are canister filters. I have coarse foam on the bottom, then medium foam, then quilt batting as a fine/polishing layer, then bio media. I've been using small size pieces of lava rock(boiled to clean it) in a mesh bag for this. It seems like that has more surface for bacteria than bio balls or ceramic rings. And it must be working fine, because my water parameters are great. Yet, I was curious if there was anything better out there. So I've been researching. While watching a youtube video about biohome media, the guy dipped just the very end of it in water to show how fast it wicks water, ergo how many pores it has for surface space for bacteria. Well I have some hyroponic grow rock from orchids that has this same property. It says it doesn't affect ph, just like bio media says. So I wondered if I'd be able to use it in my canister filter? Anyone ever tried this? Also any other tips and advice people have discovered about using canister filters is welcome! Tia!