How is the seawater filtered, prepared, and sterilized?

Seawater is collected from off the pier in Port Aransas, TX and is run through a sand filter. It is then stored in polyethylene carboys at ambient temperature in the dark until it's needed.

Seawater is diluted to 30 ppt with double distilled water immediately prior to pasteurization. Three (3) liter volumes are pasteurized in a steamer for 50 minutes. The flask is allowed to cool and left undisturbed at ambient temperature for approximately 24 hours. It is then again steam-pasteurized for 50 minutes, as on the previous day. After the flasks cools the second time, it is stored at 4 °C until it is used to prepare culture medium.