1000 watts is a kilowatt. So if you are using 841 watts each hour and the pump is running 24 hours than you are using 20184 watts in a 24 hour period. Dived by 1000 you are using 20.184 kilowatts in 24 hours. In Arizona I think I am charged 11cents a kwh so that would be $2.22 a day. It has been a bit since I played with this stuff so I could be rusty......