Two chain models, a Gaussian chain and a touching-beads (wormlike) chain, are used to represent a flexible polyelectrolyte (sodium polystyrene sulfonate) and a semiflexible polyelectrolyte (sodium alginate), respectively. Monte Carlo and Brownian dynamics simulations of those models were carried out to obtain the ionic strength dependence of some conformational and hydrodynamic properties expressed in form of equivalent radii. Electrostatic interactions were taken into account by the Debye-Huckel potential, thus counterions are not considered explicitly. In the case of the sodium polystyrene sulfonate model, a linear dependence of the equivalent radii with the ionic strength is found for a region of intermediate to low enough ionic strength values, whereas for high values of the ionic strength the equivalent radii reach a plateau with a value equal to that of the uncharged chain. Thus, an extrapolation to infinite ionic strength of the linear region would not report the actual property value of the uncharged chain. In the case of the sodium alginate model such a linear dependence is not so clearly appreciated. Our simulation results show a good agreement with several experimental data which support the validity of the Debye-Huckel approximation to model different types of polyelectrolyte solutions in a simple way.