@Carolebrdn yes! Try using hot water in the foam mix. This is what we did at the Pt Townsend workshop and it seemed to have success. They had trouble later keeping the water warm, so I think they got an electric water heater like the link below to keep the foam mix warm. You could also keep the foam mix circulating by using the little dragon without any air on and just putting the outlet of the pump back into the top of the barrel. This circulation generates some heat in the foam mix from friction in the movement.
Farm Innovators Model H-419 Ice Chaser Cast Aluminum Submergible Tank De-Icer, 1,500-Watt https://www.amazon.com/dp/B000HHO9LC/ref=cm_sw_r_cp_apa_i_DXbZDbTD8S5Q6