replacing carbon in filter

[catfish]

i have a whisper 30 filter on my 29 gallon. when i buy the replacement filter bags they come with carbon is there anything i can put in the filter bag instead of the carbon so the filtration would be better?

 

[DRaGoNoVA]

some ceramic rings? activated carbon not very gd for fishes iv heard

 

[sharks]

Activated carbon IS Fine for fish. The only thing to remember is to rinse it prior to being placed in the tank. I am a former professional aquarist with a large AZA accredited aquarium and we used Carbon for ALL FFW/RSW. When I maintained my 6400 reef or any of my observation tanks we would run carbon. Large 20,000 amazonia systems would be run with O3.