Note
Gracilaria tikvahiae McLachlan was cultured outdoors in 600 liter aerated tanks in order to determine the effects of seawater exchange and pH on seaweed yields. Under batch (noflow) conditions, seawater pH increased to 9.5 and Gracilaria yields were low (ca 4.4g dry wt m -2 day-1).Seaweed yields increased five-fold when pH control and supplemental carbon (C0 2 or NaHC03and HCl) were provided.However, Gracilaria held at pH 8.0 without CO 2 or NaHC03additions grew poorly because of total inorganic carbon(TIC) depletion from the water.