The experimental RAS comprised of four circular culture tanks (800 L each), a filtration system
(750 L) for nitrification, two protein skimmers, and a 150 W ultraviolet sterilizer. Protein
skimmers remove small particles including microlagae. Since microalgae was the oyster feed (see
Section 2.3 ), protein skimmers and the ultraviolet sterilizer were only operated for five hours a day, approximately 16–19 h after being fed, in an attempt to clean the water while minimizing the removal of microalgae