Good job with the nitrites going to zero. Nitrates will normally rise over time and is safe to about 20 ppm, which is when you should do a water change to bring it down.

Salt is used to help the fish ward off bacterial and fungal infections by helping the fish maintain it's slime coat.

I use tap water and I add conditioner to it. My water source is very hard so I have to add a Ph regulator. I was wondering, what the deal with aquarium salt? How often should it be added to your tank??

just my 2 cents..... my water levels have been ph of 6.8 ammo of 0 nitrate of 0 and nitrite of 0 for almost 2 years now not even one spike ever, the key i do a 20% water change every 3rd day, that and i have a heavily planted tank , plants always help i have a 10 g nano that i set up for a krib breeding tank too that i do the same thing to and i get the same results. once you get a good system down it take no time at all to do water changes , at first every 3rd day sounds like a pain, but i only spend about 15min total on both tanks a 55 and a 10 and like i said i have not had a spike for about 2 yrs , i even had to tear down my 55 for about a month and all i did was keep a little bit of the filter media wet and about half a 5 gallon bucket of wet gravel. and when i set everything back up it was like an instant cycle