What is it?

A simple liquid level controller, controlling the operation of two pumps based on signals from three floating switches. Exceeding the second level results in switching on the first pump. If the pump follows and pumps out the liquid below the first level, the pump stops. If one pump fails and the level rises above the third switch - the second pump starts and they pump up together until the level is less than the first switch.

Why did you make it?

The water was poured from the pond into the filter too quickly (which normally flows by gravity on the principle of liquid balance in connected vessels) and I had to pump it back to the pond (to prevent water from flowing out of the filter)

What makes it special?

Because it is simple. Simple logic - many possibilities. If you swap the order of floating switches - you will reverse the operation of the system. From now on, the pumps will monitor the liquid level and top up if necessary, not pump out the liquid as it is now.

This is a working prototype version. In preparation is the SMD version with the new system, which in the case of continuous violation of only the first level, alternately starts the pumps - The first pump now the second pump after another violation of the first level and so over and over again.

The cost of the shipment depends on the recipient's country - feel free to ask

Floating switches NOT included. I used that for the prototype. It is possible to use any contact reed / contacts as long as we combine them with a common potential.