Ammonia Toxicity & pH

Ammonia Toxicity

 

In aquaponics, ammonia is produced naturally from the breakdown of organic matter and is excreted by fish as a waste product. In fish, ammonia is a byproduct of protein metabolism and is primarily excreted across the gill membranes, with a small amount excreted in the urine.

Ammonia is toxic to fish. Many people who experience “New Tank Syndrome” experience the fish dying due to ammonia toxicity.

Ammonia occurs in two forms: ionized ammonia, NH4+, and un-ionized ammonia, NH3. Ammonia’s aquatic toxicity is principally due to the un-ionized form, NH3. As pH increases, the toxicity of ammonia increases because the relative proportion of unionized ammonia increases.

See the chart below about ammonia toxicity

    Ammonia Level in parts per million
    0.3 0.5 1.0 2.0 4.0 6.0
pH 7.0 Ideal Ideal Ideal Ideal Ideal Potentially harmful to adult fish
7.5 Ideal Ideal Ideal Potential harmful to young fish Potentially harmful to adult fish  Potentially harmful to adult fish 
8.0 Ideal Ideal Potential harmful to young fish Potentially harmful to adult fish  Potentially harmful to adult fish  Seriously harmful
8.2 Ideal Potential harmful to young fish Potentially harmful to adult fish  Potentially harmful to adult fish  Seriously harmful Seriously harmful
8.4 Potential harmful to young fish Potential harmful to young fish Potentially harmful to adult fish  Seriously harmful Seriously harmful Seriously harmful
8.6 Potential harmful to young fish Potentially harmful to adult fish  Potentially harmful to adult fish  Seriously harmful Seriously harmful Fatal
8.8 Potential harmful to young fish Potentially harmful to adult fish  Seriously harmful Seriously harmful Fatal Fatal
9.0 Potentially harmful to adult fish  Potentially harmful to adult fish  Seriously harmful Seriously harmful Fatal Fatal

Treatment for high ammonia levels

High ammonia levels need to be taken care of before fish are harmed. The first step is to do a large water change to dilute the ammonia levels.

If your pH is above 8 and you have ammonia present in your system, consider lowering the pH closer to 7. Don’t use vinegar or citric acid to lower the pH as those chemicals will harm the biological filter.