Fangrui Product Details Single-control Up Pool (water Storage) :a(red)-upper Water Level Control Point. When Water Level Gets To A Point,the Probe Contact Water And Controller Can Stop The Pump By Auto.b(blue)-lower Water Level Control Point. When Water Level Gets Off B Point,the Probe Out Of Reach Water And Controller Can Start The Pump By Auto.c(black)-should Be Placed In Bottom Of Pool As The Common Line.d(green) And E(yellow)are Connected With C (black). Single-control Down Pool(drain Water):e-upper Water Level Control Point. When Water Level Gets To E Point,the Probe Contact Water And Controller Can Start The Pump By Auto.d-lower Water Level Control Point. As Liquid Level Gets Off D Point,the Probe Out Of Reach Water And Controller Can Stop The Pump By Auto.c-should Be Placed In Bottom Of Pool As The Common Line.a And B-disconnected Lack Of Water Protection:c And D-lower Water Level Control Points. When Water Level Gets Off This Point,c Or D Probe Out Of Reach Water And Controller Can Stop The Pump By Auto.e And C-short-co