The time dependence of reaggregation of sodium alginate (SA) after following the shear-induced deaggregation of the aggregates ('egg-box' like microgel structures) at filtering through neutral 0.20 mu m filters has been found. The aggregation of SA in solution prior to filtering was induced by addition 0.1 mM Ca2+ ions. For SA at concentration of 1mg/ml and room temperature, the reaggregation process is finished after four minutes from the end of the filtration of 3.5 cm(3) of the solution with rate of filtration of 1 cm(3)/min. The reaggregation phenomenon is simply explained by diffusional driven processes of calcium ion - SA electrostatic interactions.