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.
Others have said it should be turned on so the water circulates and the water doesn't turn green. And during spring/summer, how long should the pump be on or does it have to be on 24/7? In general, you want to run the pool pump 8 - 10 hours per day in the Summer and 4 - 8 hours in the Winter. When I had my pool route in Arizona it was recommended that pump be on for 12 hours per day during the Summer.