Abstract: The system includes electrolyzers to generate acidic and alkaline effluent streams from saltwater. The electrolyzer include stacked pairs of porous anodes and cathodes that define feed channels into which reactants, e.g., hydrogen and brine, can be pumped to undergo an oxidation-reduction reaction. The porous cathode carries out the HER to generate H2, which floats upwards to the porous anode, where it is oxidized through the HOR. The reaction can thus progress in a self-maintaining manner. The HER creates an alkaline product stream with increased basicity, and the HOR an acidic product stream with increased acidity, compared to the inlet stream. Streams are pumped through the porous electrodes and the electrolyzer to sweep effluent through separate channels before they can combine. The alkaline product stream can have an alkalinity sufficient to drive metal ion precipitation in raw saltwater prior to feeding to the electrolyzer to reduce fouling/degradation of electrolyzer electrodes.