Hello I just bought a Fluval 305 canister filter. the filer came with a sponge filter and 3 trays for media with each tray split in half. The media that came with it was 50/50 Biorings and Carbon. What kind of a schedule should I have for changing this stuff out? How often should I replace it instead of rinsing? I know that Im not supposed to change it all at once so what order should I change it an when? Should I try a different configuration or type of media? I have 7 african cichlids in a 37g and any information about this is helpful. Thank you.