Newmarket uses chloramine. I use Prime as a conditioner. Sometimes the ammonia injector at the water treatment plants uses the wrong dose. I have had a whole tank of fish die when doing water changes in the spring when there is spring runoff. Then the water plant uses extra chlorine and ammonia. I now use a double dose of prime at each water change.
I have met people at the fish store who also have lost tanks of fish because of the chemical injection method the town uses.
As well I figure the Prime is a good overall cover to use when I clean the filters in case there is a mini spike of nitrates in the tanks.