I find that my tap water has about 1 ppm of ammonia because of the chloramine my district uses. To me that is meaningless. My test kit always shows about 1 ppm of ammonia in my tap water after I use my dechlorinator. About 3 hours after a huge water change I find my tank at zero ammonia. The biological filter has taken care of things. OK so where does that leave us? When a water change is first performed the ammonia levels reflect the amount my water district has added to my tap water (as a proportional part of the total tank water). A very few hours later my filter has dealt with the residual ammonia in my water and no ammonia is detectable. If I had no filter, I would need to rely on the ability of a water change to reduce the ammonia level below 0.25 ppm. If I do not have a cycled filter, I am in the position of someone with out a filter. The values I have seen for local cycled filters are not encouraging to me. Ultimately we each must do as we can to minimize ammonia and nitrite levels in our holdings.