Hi, I am new here, not sure if I should post this here but I have a question about soil, I am looking at burying the tropica aquarium plant soil, but there is a chance I won’t actually be putting any plants in the tank, it is a 20 gallon cube and the fish are neon tetras and zebra danios. Also in the filter area what should I be using, should it be just sponges, or carbon aswell, or what ? Thank you