The results of identical experiments with Navicula sp.l indicate that it is unwise to generalize based on results with a single organism. Reduction in flow occurred when phosphate concentration limited growth, but the WIBS fraction and the matrix polymer were produced throughout the growth period, as well as in the stationary phase, although the WIBS production did increase at phosphate limitation (Fig. 7). It can be seen from Fig. 8 that indeed the production of total extracellular carbohydrate polymers was correlated with reduction in flow through the bioreactors but that the correlation was not as clear cut as with Amphora. Smith and Underwood[40] using pyrolysis mass spectrometry, also showed that diatom EPS differs from species to species and, depending on the phase of growth, within species.