I think I am onto something simple.
Use an air sensing pressure switch like this
SUPCO Pressure Sensing Switch,1-1/2" D, NS2000031
It is adjustable from .1 to 1 WC setting.
It ought to sense the pressure from the pump.
It can control a contactor.
Being plastic, salt water wont corrode the internal parts.
I do not know if water would fill the interior eventually or drain out when off if it did.
I think a washing machine water level uses a similar design.
Sample Line Connector: Push-On Electrical Rating: 1/10 HP @ 120 to 277 VAC, 28 VA Pilot Duty @ 24 VAC, 125 VA Pilot
Mounting Holes O.C. (In.): 3-5/32 Type: HVAC/General Purpose
Item: Pressure Sensing Switch Agency Compliance: UL, CUL, CSA, CE
Depth (In.): 1-1/2 Function: Sense Positive, Negative or Differential Air Pressure
Application: Switching Based On Positive, Negative or Differential Air Pressure Mounting Location: Vertical or Horizontal
Package Quantity: 1 Pressure Setting Range (In. WC): 0.10 to 10.0
Height (In.): 3-1/4 Switch Type: SPDT
MPN:
NS2000031
Features: Normally Closed Terminal, Normally Open Terminal and Common Termi
Operating Temp. Range (F): -40 to 190 Width (In.): 3-1/4
Use an air sensing pressure switch like this
SUPCO Pressure Sensing Switch,1-1/2" D, NS2000031
It is adjustable from .1 to 1 WC setting.
It ought to sense the pressure from the pump.
It can control a contactor.
Being plastic, salt water wont corrode the internal parts.
I do not know if water would fill the interior eventually or drain out when off if it did.
I think a washing machine water level uses a similar design.
Sample Line Connector: Push-On Electrical Rating: 1/10 HP @ 120 to 277 VAC, 28 VA Pilot Duty @ 24 VAC, 125 VA Pilot
Mounting Holes O.C. (In.): 3-5/32 Type: HVAC/General Purpose
Item: Pressure Sensing Switch Agency Compliance: UL, CUL, CSA, CE
Depth (In.): 1-1/2 Function: Sense Positive, Negative or Differential Air Pressure
Application: Switching Based On Positive, Negative or Differential Air Pressure Mounting Location: Vertical or Horizontal
Package Quantity: 1 Pressure Setting Range (In. WC): 0.10 to 10.0
Height (In.): 3-1/4 Switch Type: SPDT
MPN:
NS2000031
Features: Normally Closed Terminal, Normally Open Terminal and Common Termi
Operating Temp. Range (F): -40 to 190 Width (In.): 3-1/4