Seachem Reef Phytoplankton is a concentrated blend of green and brown marine phytoplankton designed to provide the essential fatty acids, proteins, vitamins, amino acids with biological carotenoids for invertebrate diet. Size ranges from 1-20 µm to feed a broad range of tropical marine aquarium filter feeders and invertebrates. Reef Phytoplankton contains a natural source of carotenoids which provides essential proteins as well as a more bioavailable source of pigmentation when compared to other natural sources and synthetic pigments. Carotenoids provide the extra benefit of antioxidant activity. In addition, Reef Phytoplankton is enhanced to increase the bioavailability of important nutrients such as proteins, lipids, B vitamins and other organic pigments, thus, corals expend less energy to derive the nutritional benefit. It is blended to contain the proper ratio of fatty acids, carbohydrates and proteins. Blending phytoplankton yields better nutritional value. Comes in 500ml bottle.