We compare strategies that bring the same amount of nutrient over a given period, in terms of mean value of the biomass density over a periodic solution, and show how it can discriminate between growth functions.

The objectives of this study are twofold:

1. from an ecological view-point, determine if periodic fluctutations over or under estimate the average biomass density compared to the steady state,

2. from an biotechnological view-point, characterize the feeding strategies improving at best the average water quality.