There is a relationship between ammonia-ammonium and pH as depicted on the chart on this page:
Aquaworld Aquarium - The Ammonia and pH Relationship
the lower your pH, the less free ammonia you have, which is what can kill your fish. What you are measuring is TAN or Total Ammonia Nitrogen. So unless you keep your pH really high (like over 8.5) your actual free ammonia is not that high.
I would first check your test kit to see if it is expired.
As far as Prime goes, it is way smelly and probably nothing wrong with it - it smells like rotten eggs.
Prime "locks up" the free ammonia (NH3
) into harmless ammonium (NH4+) and then the beneficial bacteria break that down. I would find someone that has a well established tank and use your test kit on their water to make sure the kit is reading correctly.
Also, if you test right after dosing Prime, it may screw up your readings. Wait 24 hours after your PWC
and then test. Or you could try testing before the PWC
and then 30 minutes after your PWC
/Prime and then you might get a better picture of what it going on.
If you're testing that much ammonia/ammonium on a consistent basis, I would wonder if you had a pH crash or something and your bacteria colony suffered.
What kind of filtration system do you run? Have you ever changed out 1/2 of the media (bio-balls, ceramic rings, etc) and how long has the system been running?
What kit are you using?