Pool pumps
Variable-Speed Pool Pumps
Variable-speed pumps run slower for longer, which is both quieter and dramatically cheaper to operate than a single-speed pump at full tilt.
Because power draw rises steeply with speed, running a pump slowly for more hours moves the same water for a fraction of the energy. Over a season the savings often offset the higher purchase price.
Many regions now require or strongly favor variable-speed pumps for new installs. Check local rules before replacing a single-speed unit.
This page is a short orientation. A fuller write-up is on the way. In the meantime, see Pool Pumps.