Recommended Filtration Media

[crupp29]

I have a 10 gallon freshwater aquarium that I am plan on keeping a few guppies and a couple of plants in. The filter I have is the Tetra Whisper IQ. I was wondering what the best media for mechanical and biological filtration would be in my situation. Most of what I've read has said that chemical filtration isn't necessary unless there is a short-term issue or you are using tap water (which I will be). I don't know if this is important in deciding what to use or not, but the water I am using has tested 0ppm for nitrate, nitrite, and chlorine. It tested somewhere between 150-300ppm for hardness, 300 for alkalinity, and somewhere between 7.8-8.4 for pH.

 

[Essjay]

Those water parameters are fine for guppies

You can replace the cartridges with sponge cut down to the same shape. Sponge is good for both mechanical and biological filtration.
Carbon isn't needed. It's only use is to remove medication after sick fish have been treated. If you use fertiliser for the future plants, carbon will remove that as well.