It is that your tank is still in its cycle stages? Why buy inverts before your tanks cycle has completed itself? For if your tank is still in its cycling stages, you need to hold up, specially on inverts. For low levels of nitrates is for less harmful and being you left a lot of details out, I have to figure that your tank is still cycling, do not rush to stock your tank so fast and once the cycle has completed itself, you shouldn't ever see nitrites in this tank again for after the nitrites lower, as that is happening, your nitrates will rise. Being I not know how long your tank has been setup, I have to figure that its been setup for about five weeks now??
When you tank completes the full cycle, all readings will then be at zero, the ammonia, nitrite and nitrates would all be at zero with nitrates being last of course.