no, ammonia is different. Ammonia is produced by fish waste, uneaten food and anything decaying in the tank, like plants. Good bacteria form to process the ammonia, which then turns into nitrite; and yet another form of good bacteria process the nitrite into nitrAte. Ammonia is the most toxic, and nitrite is toxic as well. Nitrate is fine in low levels, aim to keep it around 10 or under.
Get an ammonia test kit, preferably an
API liquid test. It is probably the most important tester for the tank.
Your ph of 8 is fine. But keep it stable.
Test your tap water and see what the tap ph is.
Doing weater changes regularly, even small ones daily or every other, is a good way to maintain stable water chemistry in your tank, including a stable ph. Not everyone does this, some prefer to do one large change once a week. For me, I choose to do several small ones frequently, in addition to the larger one when I vacuum the tank. It's personal preference.
If you choose to do larger water changes once a week, just make sure the ph of the new water going into the tank is close to the existing water in the tank. Even small ph differences can shock or even kill fish.
So for instance, let's say your tap water is 7 ph. To do a water change, you'd have to do it slowly, adding water a bit at a time, as not to shock the fish.
BUT if you do small water changes frequently during the week, the ph will stay fairly close to the tap. See what I mean? Then you don't have to worry about a big fluctuation at water change time.
Of course, there are reasons why ph could fluctuate up and down in aquariums, but there's no need to get into that since that doesn't seem to be a problem you are having.
Yours is staying at 8, correct? If it is, that is fine.
!!!! I just would like to caution that the ph up and down chemicals that are used, can kill any beneficial bacteria 
so as joy recommended, getting an api liquid master test kit is important to know where your tank parimeters are daily...if you can also find either prime, amquel+ or ammo lock, that will be a huge benefit to the fish if you arent fully cycled...doing partial daily water changes with one of those will detox the ammonia and nitrites (if you get them from using the ph chemicals) which are deadly to fish, for 24 hours until another water change.....do you have a nitrate reading when you tested?