Comparative evaluation of natural water conditioners for their potential use in freshwater aquaculture

In this study, the use of natural adsorbents, such as zeolite (clinoptilolite), leonardite, and duckweed (Lemna minor, L. 1753) was investigated for the regulation of optimum water qualities in freshwater aquaculture. The study was carried out in 3 experiments in triplicate. In the first experiment, aquarium fish feed (35% protein) was used as the ammonia source at 3 different rates (0.2, 0.4, and 0.6 g feed per 500 mL of tap water). In the second experiment, clinoptilolite (C) and leonardite (L) mixture (C:L = 1:2) were added to balance excessive ammonia. In the third experiment, duckweed (1.5 g/500 mL) was added to aquaria (10 cm in diameter) in a way to cover the surface area, and the ammonium adsorption of duckweed at low NH₄⁺-N concentrations was determined with 9 measurements. In this study, NH₃ values reached their peaks (0.19 mg/L) at the end of 1st experiment, in which ammonia values originating from the unconsumed feed were determined. In the 2nd experiment, NH₃ values began to decline (0.06 mg/L) with the addition of natural adsorbents (zeolite + leonardite) and were decreased to 0.003 mg/L with the addition of duckweed in experiment III, where natural adsorbents started to reach saturation. When the data obtained at the end of this study were evaluated, it was determined that all 3 natural materials had a positive effect on water parameters in aquaculture systems. As a result, it was determined that in high concentrations of zeolite + leonardite mixture and in low concentration of duckweed there had been a good removal efficiency.