Abstract: A pool cover for temperature regulation of pool water having an upper sheet of flexible material and a lower sheet of flexible material. The sheets are joined together at their side edges and along a plurality of longitudinally seams to form a panel having a plurality of longitudinal seams to provide a plurality of flow channels. A pump attached to an input tube draws in water from the pool, and via an input manifold forces the pumped water through the flow channels in the panel, and out the ends of the flow channels back into the pool. Pool water pumped through the flow channels picks up heat from incident solar radiation and the ambient air temperature, or gives off heat to the ambient environment, depending on the temperature of the air, the amount of incident radiation, and the temperature control settings provided by the user.