An ammonia test kit with the wrong kind of active agent may give a false positive reading even after the ammonia has been detoxified. These kits are available at aquarium supply stores. It is important to test your pond water to make sure there is not a build-up of ammonia. Unlike chlorine, chloramines do not dissipate to the atmosphere by standing or aerating. Boiling will not remove chloramines.
Chloramines pass through the gills of fish and directly into their bloodstreams.
In the blood, chloramines chemically bind to the iron in the hemoglobin in red blood cells causing a reduction in the cells' capacity to carry oxygen. Sodium thiosulfate added to chloraminated water will neutralize chlorine, but ammonia is released into the water. Water should ideally be dechloraminated in a separate container to neutralize chlorine and ammonia before being added to a tank or pond. Tap water used with artificial sea salts for makeup water in salt water fish tanks must be dechloraminated. The proper amount of neutralizing chemical is sometimes added to the pond prior to or simultaneously with the makeup water.