Ammonia in tap water using Prime

[twoodrough]

I have a 10 gallon with a female cherry, zebra danio, and pearl gourami. I am considering adding another small fish but want to make sure the bacteria is taking care of the ammonia. Using the liquid API I checked the water in the tank. It came up 1.0 ppm. Not good. I checked the source water and it came up with ammonia as well. I checked the water from my separate 1 gallon betta tank and it came up fine. If I added one drop of prime in a 5ml test tube the ammonia seemed to go away. So I thought I am just not using enough prime. So in a 3 gallon tub I started adding prime to see how much I had to use before the ammonia did not register. I started with 1 ml, then 2 ml, then 3 ml. And the results are all the same (green). I stopped at that point to think about what could be going on. Nitrites are 0 (blue) and nitrates are reasonable (light orange). Any ideas? All I want to do is add one more fish to this tank but I can't get a zero reading for the ammonia

 

[BrackAttack]

How often do you do water changes and how much do you change. Your BB should convert the ammonia. Maybe you could add a small air powered filter with ammo chips to your water that your going to use for pwc.

 

[torres]

prime will turn ammonia to ammonium for about 24 hours!
just when you bacteria take it all out you wont get any reading.