Flow-through
(4) Flow-through means a continuous or an intermittent passage of test solution or dilution water through a test chamber or culture tank with no recycling. (5) Immobilization means the lack of movement by the test organisms except for minor activity of the appendages. (6) Loading means the ratio of daphnid biomass (grams, wet weight) to the volume (liters) of test solution in a test chamber at a point in time, or passing through the test chamber during a specific interval. (7) Static system means a test system in which the test solution and test organisms are placed in the test chamber and kept there for the duration of the test without renewal of the test solution.