The Effects of Temperature on Maintaining the Stability of Water Quality in Biofloc-based Zero-water Exchange Culture Tanks

Abstract

This study explored adequate water temperature ranges for maintaining stable water quality in a biofloc-based zero-water exchange culture system. Five experimental tanks with the following temperatures were set up: 10℃, 15℃, 20℃, 25℃, and 30℃. First, a biofloc-based culture system was developed in the experimental tanks; then, the tanks were stocked with goldfish and went without a water exchange for 60 days. Conditions for developing a biofloc-based culture system and stable water quality in low concentrations of inorganic nitrogen compounds at 10℃, 15℃, 20℃, 25℃, and 30 o C were maintained after 17, 26, 43, 68, and 78 days, respectively. Beginning from when the goldfish were stocked in the biofloc-based culture tanks, concentrations of NH4 + -N remained constant and at low levels at 10℃ and 15℃, but they showed a gradual increase at 20℃, 25℃, and 30℃. Concentrations of NO2 --N and NO3 --N at 10℃ and 15℃ did not remain at low levels and immediately increased. While NO2 --N concentrations at above 20℃ remained constant and stable at relatively low levels, NO3 --N concentrations showed a gradual increase. Conditions of 15℃ and below could not maintain low and stable concentrations of NO2 --N. In the pH range of 4.0 to 6.0, NH4 + -N concentration decreased as the pH rose. However, there was no correlation between pH and NH4 + -N concentration in the pH range of 6.0 to 8.0. These results indicate that pH levels should be kept at pH 6.0 and above to maintain a low and stable concentration of NH4 + -N at above 20℃.

Biofloc technology in aquaculture: Advantages and disadvantages from social and applicability perspectives – a review

“…In a study conducted on goldfish, different temperature values were compared and it was reported that the survival rate and growth rate were significantly lower at 10 and 15°C. In addition, ammonium nitrogen was observed to be higher at low temperatures (Cho et al, 2015). The highest survival rate, growth performance and water quality were observed at 25 and 30°C temperatures.…”

Comparative study on growth of leafy vegetables grown in a hybrid BFT-aquaponics using Japanese eel, Anguilla japonica and hydroponics

“…Furthermore, the introduction of a RAS for high density and rapid growth of eel may cause an increase in infrastructure costs. Eel is cultured at the range of water temperature of 25℃-30℃ throughout the year, therefore, it is applicable to the BFT aquaculture (Cho et al, 2015).…”

Availability Verification of Effluent from BFT Inland Aquaculture for Urban Agricultural Fertilizer through Cherry Tomato Cultivation

“…According to the research findings that composting of aquaculture effluents as agricultural recycling includes many organic matters such as nitrogen and phosphorus in the fish excretions (Kim et al, 2016a), aquaculture effluent perceived as a water pollution source (Lee, 2001;Subramaniam et al, 1994) can be used as a concept of a virtuous cycle of resources. The aquaculture effluent used in this study was discharged from a farm that applied biofloc technology (BFT), which is an eco-friendly farming technique that reduces water pollution by removing excess organic nitrogen in fish excretions and remaining fertilizers using biofloc in the water treatment process of the farm (Cho et al, 2015). In particular, effluents from inland water culture applying BFT contain organic nitrogen or phosphorus necessary for plant growth, and thus can be used as a useful resource in cultivating crops (Kim et al, 2016a).…”