Well....
I've been doing FW for 20+ years, and the only way to keep the amonia and nitrates down is "vaccum the poo".
I did many "bare bottem" tanks with filters, but as long as you have rock/gravel, you will need to "vaccum the poo"
Water changes also must be done, so when cleaning the gravel, just fill the tank back up.
If you were to go with sand on the bottem, go with about one inch and a good bio-wheel filter. Then the filter will take care of the poo. (no under gravel type setup). You will still have to do water changes though.
Tagg____