Manipulated seawater from the four header tanks was delivered to experimental units at a rate of ∼6 l h−1. Each experimental unit was directly fed from one of the reservoir with an individual pipe. The water entering the experimental set-up was designed to fill independently each experimental unit, overflow in the aquaria, and be discharged from the aquaria through an additional overflow system. pH and temperature stability in experimental units was checked every two days during the whole experiment using a glass combination electrode (Metrohm, electrode plus).