Sw tanks seem to balance themselves more easily then few. Largely imo due to live rock. If you don't want to worry about ammonia in a tank make sure there is enough bacteria colonized in your tank to eat it up and convert it. With sw live rock is bacteria central
Beth she said nitrites at zero, not nitrates. Could be a typo tho. In almost any tank there will be nitrates
Stirring up the sand is a big no no tho. All kinds of toxic stuff gets trapped in there
While not cheap adding some fully cured live rock will help. The bacteria your trying to add is already established on it. That will help consume the ammonia and break it down. Dry is fine but takes much longer then dry seeded with a few lbs of live rock.
In my area wny, most retailers treat fish tanks w copper. They then keep, snails,shrimp, stars,ect in separate tanks. However to save space some do keep disease resistant fish (draggonetts) with that stuff aswell