What Filter Media to use for Fluval 405 with Piranhas?

I have 4, 4-5 inch Red Belly Piranhas in a 36g tank. Im getting a Fluval 405 this week. The water in my tank always looks dirty and foggy with the Aqueon filter for up to 45g that im using right now. What kind of Filter Media should I use for the Baskets? or is the carbon and bio max Sufficient? Another thing i was wondering was that if I should leave both filters running for the bacteria and if so for how long?