The purpose of this study is to compare the characteristics of water quality for pH control and algal bloom prevention between oyster shell loess balls and commercial filter media to identify the possibility of utilization as filter material in an ornamental fish tank. The porosity of the SL filter material produced using an oyster shell was 65.33 %, NM was 63.67 %, CP was 87.67 %, and YK was 50.67 %. In the case of SL, the higher the porosity, the greater the specific surface area that can be contacted in the water, and the attachment of microorganisms becomes easier, so it is judged to have suitable conditions for use as a filter medium. The reaction time was varied from 50 g of the injection amount of the filter medium to pH 6.5 and measured for 0 to 120 hours to compare the water quality characteristics. Commercial filter media showed a range of pH 7.2 to 7.5. SL increased to pH of 11.8 at 120 hours, indicating that the range of pH increase was greater than that of commercially available filter media. The PO₄-P removal rate according to the reaction time was found to be in the range of about 10.0 to 25.2 % for commercial filter media. SL showed a high removal rate of 98.1 % after 12 hours, and close to 100 % after 24 hours. The pH was set to 6.5 and the injection amount of the filter medium was varied from 25 to 100 g the reaction was performed for 24 hours. SL is pH 9.66 ~ pH 10.46 and commercial filter media was found to increase to pH 6.6 ~ pH 7.77. The removal rate of PO₄-P was about 100% when more than 50 g of SL was injected, and commercial filter media were about 10 to 25 %. After adjusting the initial pH to 5~9, 50 g of the filter medium was injected, and the change in water quality was measured after 24 hours. commercial filter media were found to be pH 6.90 ~ pH 8.40, SL was pH 9.77 ~ pH 11.60. The PO₄-P removal rate showed that SL showed a removal rate close to 100 % regardless of the pH condition.