Hello
Your water parameters should be as follows IN A FULLY CYCLED ESTABLISHED TANK:
Ammonia: 0
NitITE: 0
NitrATE: less than 40ppm
Ph: Anywhere from around 7.4-7.8
Temp less than 20 degrees celcious
Now, as for your filtration, let me get this straight. You are doing a water change every second day in your AXOLOTL tank which has NO filtration. You discard of the water you are taking OUT of the AXOLOTL tank and throw it away. You then use aged water from a separate tank that has NO LIFE FORM in it but has two filters and put this in your AXOLOTL tank to complete your water change, yes??
If that's the case, I can't imagine either of your tanks are cycled - you have no life form in the tank with a filter (which would be the cycled tank) to create ammonia and therefore kickstart a cycle and since you are using prime it removes the ammonia that is originally in the tap and detoxifies nitrite and nitrate.
Adding commercially available bacteria won't help either until you either A. add ammonia to the tank on a regular basis or B. add life forms to the tank to create and sustain a cycle.
Also, while any ammonia is not ideal. Up to .25 if barable. Its above .25 that problems can begin. And your nitrate is perfectly safe at just 5. So I'm not sure what "auntiejude" was on about unless she misread and thought you had typed nitrite - easy mistake.