Abstract: A sensor includes a hollow tube having first and second ends; a cap secured at said first end; said second end being substantially open to allow fluid to enter the tube; a floatation element slidably arranged within said tube; means at said second end for preventing the floatation element from leaving said tube; a contact switch arranged within said tube between said cap and said floatation element; and a fluid exhaust means provided in said tube adjacent said contact switch. The sensor may be used to detect a motion or displacement of water in a swimming pool.

Abstract: A sensor includes a hollow tube having first and second ends; a cap secured at said first end; the second end being substantially open to allow fluid to enter the tube; a floatation element slidably arranged within said tube; an element at the second end for preventing the floatation element from leaving the tube; a contact switch arranged within the tube between the cap and the floatation element; and a fluid exhaust opening provided in the tube adjacent the contact switch.