Hence the relatively small projected sea level rise by the year 2100, as compared to the changes measured in tens of meters that occurred in Earth's history (see Introduction). The rise by 2100 is only a small beginning of a much larger, multi-century response of ocean and ice sheets to elevated global temperatures.
Single Speed Pool Pumps: Runs at a single speed, 3450 rpm (revolutions per minute). Imagine if your car ran at 3450 rpm - all the time, and how much gas you would use! Dual Speed Pool Pumps: Have a fourth wire coming into the pump, the low speed wire. This allows you to run the pump on low speed for 8-16 hrs per day, and high speed for 4-8 hrs. Variable Speed Pool Pumps: Operates at many speeds, programmable and self-optimizing for the highest energy efficiency and greatest energy savings.
As a general rule, most pool guys will tell you to run your pool pump 4 - 6 hours in the Winter (provided you don't winterize your pool) and 10 - 12 hours in the Summer for best filtration. Many people do this at night because in parts of the country the electricity is less during the evening hours.