The following formula can be used to figure out power cost for your area.
Cost per hour= Kilowatts x cost per kilowatt/ hour.
Example: If your bubbler consumes 0.91Kw and you pay 5 cents per kilowatt/ hour then the cost per hour would be 0.91×0.05=4.55 cents per hour or if run for a full 24 hours it would be $1.09. In areas with time of use hydro rates the same formula will work if you calculate the cost for each block of time and add them to get your daily total.