The effectiveness of chemical-free water treatment system combining fibre filters, ultrasound, and UV for fish farming on algal control

A chemical-free water treatment system consisting of fibre filters, ultrasound, and UV for fish farming was operated in a fishpond to study its effect on the control of algae compared with a non-treated fishpond. Phytoplankton and phytobenthos were sampled in both ponds, at the same time Chlorophyll-a, nitrates (NO3), orto-phosphates (PO4), pH, water temperature and saturationwere monitored. The results showed that ultrasonication caused efficient sedimentation of planktonic algae. The number of determined algal species was lower in the treated pond. The proportion of green algae and Cyanobacteria was higher in the non-treated pond, and diatoms were the predominant group of algae in the treated pond. The species Oedogonium sp., Mougeotia sp. and Spirogyra sp. were 'tolerant' to ultrasonic irradiation. The successful control of algae using the chemical-free water treatment system suggests that the Chem-free water treatment system can be a practical method to control algal bloom in fish farms.