Where does ammonia come from?
Pond fish continuously release ammonia into the water from their gills (at least 75% of the ammonia comes from the gills), urine and solid waste. Uneaten fish food and decaying algae also release ammonia. Ammonia is toxic to all fish. Left untreated, ammonia damages delicate gill membranes and prevents the fish from carrying on normal respiration. High levels of ammonia quickly lead to fish death. Even trace amounts of ammonia can stress fish, suppressing the immune system. This causes a gradual decline of fish health and leads to outbreaks of disease in the pond.
How the presence of ammonia can be detected in the pond.
..Fish stress and labored respiration are just two indications that poisonous ammonia may be present in pond water. Because ammonia is colorless and odorless, pond water should be tested weekly. If ammonia is present, steps must be taken to remove it.
What happens to the ammonia?
Dangerous ammonia (NH³) is converted to harmless nitrate (NO³-) through a process called the "Nitrogen Cycle". Normally, an active biological filter, comprised primarily of nitrifying bacteria, consumes ammonia. Some species of nitrifying bacteria convert ammonia to nitrite, which is also toxic to fish. Other nitrifying bacterial species convert nitrite to harmless nitrate. Together, these bacteria create a healthy, mature biological filter, which keeps the pond free of harmful ammonia and nitrite. In newly established ponds, however, the biological filter takes several weeks to develop. Ammonia may build up to toxic levels during this time, underscoring the importance for water testing to protect the fish. Even in established ponds, ammonia levels can become toxic from accidental overfeeding, from an unnoticed fish death, too many fish, not enough filtration, or when there is a rapid die-off of algae. A healthy pond should have no detectable ammonia, as ammonia is toxic to all pond life. To reduce the toxicity of ammonia, use Amquel or Ammo-Lock2.
If at any time ammonia is detected take steps to reduce ammonia, such as clean the pond bottom of excess debris and stop fish feeding. Make sure adequate oxygenation and surface agitation are provided. Use either Amquel or Ammo-Lock2, add a bio booster such as Microbe Lift, Ki Nitrifier, Crystal Clear Beneficial Bacteria, or Pond Zyme. Also make a 25% water change every two days until the ammonia level drops to zero.