6.7 Corrective Measures

• Low dissolved oxygen (below 5 mg/L): increase aeration, reduce feeding until corrected

• Low pH (below 6.0): add base (calcium hydroxide, calcium carbonate, potassium hydroxide or potassium carbonate), reduce feeding until corrected

• High ammonia (above 1 mg/L TAN): reduce feeding until corrected, perform 20% water exchange, check for accumulated solids, increase biological filtration

• High nitrite (above 0.5 mg/L): reduce feeding until corrected, perform 20% water exchange, increase biological filtration

• Consistently high nitrate: reduce fish biomass or feeding rate, add more plant biomass

• Nitrate consistently at zero: increase fish feed or fish biomass

• Low alkalinity: add carbonate bases ex. (calcium carbonate, potassium carbonate)

*Note: Adding any base to the system must be done with care. Small additions of these chemicals result in a large increase in pH. Base additions should be calculated before addition. Always err on the side of caution.

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.