The purpose of this study is to investigate possibility of the pH control and nutrients removal for efficient management of water quality in aquaculture of ornamental fish. Specific conclusions derived from this study are as follows.
When the oyster shell and ark shell were put into the reactor from 3 kg to 40 kg per ton, the pH was gradually increased from 6.5 to 8.5. But there was no difference between the shell kind for pH control.
When the calcined shell added to loess ball was put into the reactor, the pH value was increased with the increment of shell content and the lower calcination temperature.
When the shells content were over 3 kg non-calcined shell, the pH value was increased to 8.5. On the other hand, pH value was increased over 7.6, when the calcined added to loess ball was put 1kg over per ton.
When oyster shell and ark shell were put into the reactor from 2kg to 4 kg, the removal efficiency of phosphate was slightly increased with the elapsed time. More than 80 percent was removed, when 40kg of shell was put in 15 days. But nitrate was just a little removed regardless of shell content and shell kind.
When 3 kg of the calcined shell added to loess ball was put, 99.9% of phosphate was removed. But the removal of nitrate was not happened.
Therefore, it is possible to control of pH and remove the phosphate using shells in aquaculture of ornamental fish. But when the calcined powder of shell was used, rapid pH raising led to stress to ornamental fish. so it we use the loess ball added calcined shell, it is possible to control of rapid pH and large amount of Hydroxyapatite sludge by mitigation of leaching of calcium ion.
From now on, we want to study about the verification experiment on mixing ratio, filtration efficiency and management using shells.