The flow-through experimental system consisted of 15×8.5-L
polyethylene tanks situated in a 220-L water bath, arranged in 5 rows
of three tanks with treatments dispersed randomly. The water bath was
maintained at approximately 18 °C with a 1-hp chiller and re circulation pump
Three 60-L header tanks were used to precondition sea water
closer to the desired temperature and each supplied five tanks.
Multiple 100 to 300-Watt heaters were used to thermostatically maintain the
desired temperature within each header tank, and float-valves were
used to regulate the supply of fresh seawater. All experimental tanks
were supplied with a continuous flow of thermally preconditioned
seawater, receiving 5 to 8.5 exchanges of total volume daily. Each tank
contained a 100-Watt heater placed in a length of 25-mm PVC pipe with
an air-diff user stone mounted in the base. This thermostatically ensured
homogeneous water temperature through consistent water movement
and maintained dissolved oxygen levels. Excess water from tanks
overflowed into the water bath, which in turn over flowed to waste.
Water quality was maintained by the use of flow-through
seawater supplied by the seawater system at the NMSC, which is
drawn from a beach intake and pre-filtered to 30 μm. A photo period of
12 h light:12 h dark was controlled by timer switch to four fluorescent
lights, 1.6 m above the tanks.