6. Water Quality Parameters

Understanding water chemistry in aquaponics is essential to providing optimal growth conditions for the fish, plants, and bacteria. By culturing fish in a recirculating system, all the essential elements for survival--- such as temperature, oxygen, pH, and water clarity--- need to be provided. Like all organisms, those cultured in aquaponic systems have optimum ranges for growth and survival. While there is overlap between optimum water quality ranges for each organism, a compromise must be made in many aspects of production (Table 6).

Table 6: Recommended water quality parameters for aquaponics*.

OrganismTemperature (°C)pHAmmonia (mg/L)Nitrite (mg/L)Nitrate (mg/L)DO(mg/L)Warm water fish22 – 326 – 8.5< 3< 1< 4004 – 6Cold water fish10 – 186 – 8.5< 1< 0.1< 4006 – 8Plants16 – 305.5 – 7.5< 30< 1< 250> 3Bacteria14 – 346 – 8.5< 3< 1-4 – 8Compromise for Aquaponics18 – 306 – 7< 1< 1< 1505 – 8

*Reproduced and adapted from FAO small-scale aquaponic food production (Somerville et al. 2014).

The five most important water chemistry parameters to consider for aquaponics are dissolved oxygen, temperature, pH, total ammonia nitrogen, and alkalinity.

• 6.1 Dissolved Oxygen
• 6.2 Temperature
• 6.3 pH
• 6.4 Total Ammonia-Nitrogen
• 6.5 Alkalinity
• 6.6 Cycling the System
• 6.7 Corrective Measures

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