Title: Variation of total ammonium nitrogen in an aquaponics system fitted with bio-filter media.

Without vital information on maintenance of water quality balance, the concept of aquaponics becomes challenged and unprofitable. A study was conducted to investigate the viability of bio-filter media to an aquaponics setup. NH₄Cl was used at varying concentrations (0.3, 0.6 and 0.9 mg/L), in setups with and without biofilter media. A noticeable change in water quality and plant parameters happened after day 3. After 10 days NH₃ and NH₄⁺had reduced to 0mg/L. More NH₄Cl was added. After day 14 setups with biofilter media had more NH₄⁺and less NH₃ in contrast to setups without biofilters. NH₃ ranged between 0.0046±0.003 mg/L to 0.011±0.008 mg/L in setups with biofilters; and 0.006±0.006mg/L to 0.014±0.01mg/L in setups without biofilters. NH₄⁺ ranged between 0.20±0.1mg/L to 0.50±0.34 mg/L in setups with biofilters; 0.26±0.1 to 0.46±0.4 in setups without biofilters. DO was constant in all setups with a mean 9.88±0.12 mg/L. Water temperature ranged between 16.1°C to 18.4°C. pH ranged between 7.8±0.01 to 8.11±0.9. There was an increase in the number of leaves per tank. Without biofilter media the conditions tended toward basic and so shifted the balance of NH₄⁺ to more NH₃. Biofilter media provide more surface area for multiplication of bacteria which in turn act on NH₄⁺ to other forms like nitrates which are beneficial for plant growth and thud cleaning the aquaponics system. The balance in water quality parameters favours plant and fish growth hence profitability to the farmer.