I am not a pump expert, but electricity is my thing. 230 VAC is more efficient than 115 VAC. The pump will consume the same power, yes, but power loss in the conductors from the power source to the pump is equal to I²R (current squared x resistance). At 230 volts, the current will be half as much as at 115 volts, and the resistance of the conductors will be the same. So conductor power loss will be 1/4. Having said that, unless your conductor runs are REALLY long between the wall and pump, you will notice no appreciable difference. No bearing on your use case, probably, but I felt the need to share.