The Alga growth inhibition test ISO 10253 in the marine environment employs the species Phaeodactylum tricornutum (Chemex preferred species) and Skeletonema costatum.

The growth inhibition test is performed semi-axenically (i.e. minimising contamination by other organisms) in glass flasks under controlled conditions.  Growth of the alga is determined by cell counting or spectrophotometry at 24-hour intervals for periods of exposure up to 96 hours. The data are used to determine the LC50 value for growth-rate. The highest no effect concentration (NOEC) is determined using appropriate statistical procedures.