Not a good idea. The use of salt is debated, but here on AC the general consensus is that it isn't necessary nor useful unless battling ick.iv had the tank up for months and i have not changed a thing. Everything i do now is the same as when i first set it up. I think ima add some salt and see if that will help.
Also, if your test kit doesn't read exact numbers, then I doubt you are really cycled. Get yourself a good liquid test kit or take a water sample to the LFS.
If the levels aren't:
Ammonio: 0
NitrIte: 0
NitrAte: <40
That's probably your problem.