So the oil tank level indicator got me thinking...I know I said an Arduino solution will be what I would do, But I have a water tank way up in the corner of my garden. Water and electronics are not friends and being outside the day and night temp difference will cause a lot of condensation on the top.
The solution .....a mechanical one. So you can just add a weight and a float and some small pulleys and have an inverse of the water level on the outside. I did not want that. I wanted to see where the water level is.
The solution...Add an extra weight and a pulley and use a float that you can adjust its weight, but still keep it floating. A Coke bottle in my case.
I think a picture is more explanatory than a lot of words. The indicator is now attached to the extra weight and shows the actual water level.Now you can understand why you must be able to adjust the weight of the float. It must be heavy enough to lift the extra weight. I used some more old number plates and a hole saw to create my small pulleys and an old piece a ali shower door extrusion as the frame for the contraption.
Not really a "TOOL" but a solution to NO problem.