So I've been doing a lot of water changes lately because I thought my aquarium was going through a mini cycle. When I tested the water the ammonia showed up as somewhere in between 0 and 0.25. However when I tested after a 50% water change the levels were the same. Finally I tested my tap water and found out it showed the exact same color as my aquarium water. My question is, can tap water have ammonia in it? If so, is a range of 0-0.25 ppm ammonia going to harm my fish over time? Attached is a photo of my results, tap is on the right.