Goals of this study are to point out strategies to influence the gel-matrix building components of biofilms. One well characterised component of the extracellular polymeric substances (EPS) of the bacterial strain Pseudomonas aeruginosa SG81 is the alginate AlgSG81. AlgSG81 is one main component of EPS and thus of the gel-matrix, too. AlgSG81 is completely dissociated in aqueous solution and therefore a strong polyelectrolyte (PEL). By means of computation with OSF-theory and validation via viscosity measurements the conformation of AlgSG81-chains in aqueous solution at screened and not screened conditions is that of a coil over a large concentration regime. By addition of tetramethylurea (TMU) to aqueous solutions of AlgSG81 the formation of a physical network (gel) is observed. Different empirical and theoretical approaches to characterise PEL were improved and experimental verified.