Microbiofotling in Simulated Ocean Thermal Energy Conversion Heat Exchangers with Surface and Deep Ocean Waters in Hawaii

a 2-year period a tenacious film formed. Daily free passage of sponge rubber balls through the tubing only removed the loose surface biofouling layer and was inadequate as a countermeasure in both titanium and aluminum alloy tubes. Chlorination at 0.05, 0.07, and 0.10 mg liter-' for 1 h day'1 lowered biofouling rates. Only at 0.10 mg liter-' was chlorine adequate over a 1-year period to keep film formation and heat transfer resistance from rising above the maximum tolerated values. Lower chlotination regimens led to the buildup of