In another pilot study it was found that increasing depth of water column from
600 to 850 mm resulted in a increasing mass transfer effect of a particular aerator,
but we were constrained by overflowing waves, as the basin was only 900 mm deep.
For on-going tests the water filled to no more than 750 mm, specifically as recorded
in Tables 1–3 Some water escaped with splashing at higher speeds, so the levels
decreased until the tank was refilled. The tank was drained and water was replaced
well before total dissolved solids accumulated to the 2 mg/l maximum concentration
allowed in the standard (ASCE, 1993).