The tether float gets obstructed from movement easier; the switches require more frequent replacement, however, the pump is cheaper.
The vertical float is protected against obstruction of movement; the switch requires more frequent replacement than a diaphragm or probe but less than the tether float. Some brands offer the ability to change the switch without removing the sump pump fom the pit.
A diaphragm and probe are very dependable and require less service.
Company Resource: Mini-chillers Industrial Air Conditioner Modular Air Conditioner
Read more: http://www.cn-skysea.com/Blog/