Fresh water tank gauge

[RhumbleFish]

I’m not sure I understand that. How does it know which two bolts to read?

It's just closing a circuit...

 

[Charles Reese]

Well went back out today to flush out the bleach solution and refilled with water and it read full tank! Yah! But not to fast did a couple things outside and went back in and just as fast it went to empty . I’m done with it, thanks for all the comments and suggestions