when it comes to setting up a fish tank it would be very helpful to have some very porous rocks in there. what you want to be able to do is set up a place where you can grow a nice bacteria colony to break down the ammonia and start the nitrogen cycle. you can also use scrubbing pads but depending on how often you clean out your tank those will accumulate too much food waste and is bad for the fish. i have experience with salt and fresh water, along with various corals. I used to help my brother tend his small coral farm as well.