Rule computerized pool cover pumps, sump pumps and utility pumps remove water from pools, pool covers, basements, garages, utility rooms, stairwells, sumps, boats and other utility applications. Rule Pumps feature computerized operation on the principle of impeller resistance. Float switches are not required. The pump will turn on every 2-1/2 minutes to sense for water. If water is present, the pump will sense resistance and continue to run until all the water is removed. Thereafter, it will check for water every 2-1/2 minutes.Power use in the checking mode is minimal.