Have you tested your tap water for ammonia? It is not uncommon for some municipal water sources to contain scant amounts of ammonia.
The difference between 0.25 and 0.5 ppm is very hard to detect. I wouldn't fret about it too much. Now if it jumped from 0.25 to 1 or 2 ppm that would be more of a concern.
The difference between 0.25 and 0.5 ppm is very hard to detect. I wouldn't fret about it too much. Now if it jumped from 0.25 to 1 or 2 ppm that would be more of a concern.