The ISO 10253 standard specifies the test method for marine algae growth inhibition using Skeletonema sp. and Phaeodactylum tricornutum. This test aims to assess the inhibition of marine algae growth by contaminants that may be present in water quality, thus reflecting the potential impact of water contaminants on ecosystems. By measuring the algae growth Depression effect of contaminants at different concentrations, it is possible to help identify substances in water bodies that may be toxic. This standard provides standardized experimental procedures to ensure the accuracy and repeatability of test results, providing a scientific basis for marine water quality monitoring and environment protection.