Well, first, that tank is too small for an adult turtle. She really needs a 75 to 100 gallon aquarium if she is an adult of 7 inches or more. So she is producing a tremendous amount of waste. She definitely needs a 50% water change once a week, and I would recommend no gravel, only a few large rocks she can climb on, and sleep under, or a large piece of driftwood.
As to media, foam goes on the bottom, then the carbon, then the bio balls. The carbon will help remove odor, but you may need more foam to help with overall filtration. This filter is rated for up to a 30 gallon fish tank. For a turtle tank, we would have suggested the 220 considering her species and size. Adult females reach 12" in diameter. I use the 360 in a 90 gallon tank with a 7" cooter.
Do a large water change, and make sure she is eating all of the food you give. Water should be around 3/4 of the way up in the tank to give her the most room for swimming.
Date published: 2017-04-03