We show that buoyancy-driven spatiotemporal pattern formation can be conveniently tuned by varying the ratio of the initial concentrations of the reactants. The increase in the stoichiometric excess of chlorite even leads to the reversal of the sign of the net density change during the reaction and hence the originally unstable downward propagating reaction diffusion fronts can be stabilized. The dispersion curves quantitatively characterizing the density fingering are in good agreement with the observed behavior. (C) 2013 Elsevier B.V. All rights reserved.