The nine experimental aquaria were exposed to natural sunlight from above and
the sides were covered by insulating material to prevent
light entering laterally. Nutrients were supplied to each
aquarium as analytical grade anhydrous NaH2PO4 amounting
to a phosphorus load of 100 μg/(L·week); and KNO3
equating to a nitrogen load of 2 mg/(L·week) (expressed as
N). In the event of rain, a plastic greenhouse was brought
in to shelter the experimental setup and was moved away
immediately when rain ceased.