Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Nitrifying bacteria will grow on most surfaces that are used in the filter. Sponges, floss, activated carbon...
So if you have any sort of sponges and floss, then you already have homes for the beneficial bacteria.
To add more bio filtration, I would add lots of plants, and do my best to keep the plants happy. (light, CO2 and other nutrients) rather than trying to grow more bacteria.