For level sensing I recommend this submersible sensor:
https://www.aliexpress.com/item/1005007144609372.html
Available from a number of suppliers.
It has a 4-20mA interface, which means you can put the sensor 100m away at tank 2. It just drops down into the bottom of the tank.
You could use the same sensor in tank 1, then you need two 4-20mA converters at your controller. Presumably you don't need too much smarts in the controller. It's basically "fetch two tank levels" "if tank 2 is low, and tank 1 is not - run the pump" "if tank 2 is high or tank 1 is low or the pump has been running for a while - stop the pump".
You don't need a Pi for this. A simple micro and some LEDs would suffice. You can optionally export the tank levels and pump status out of a serial port for something else to log, and display on a nice web gui, but really, the less there is, the less there is to go wrong.
https://www.aliexpress.com/item/1005007144609372.html
Available from a number of suppliers.
It has a 4-20mA interface, which means you can put the sensor 100m away at tank 2. It just drops down into the bottom of the tank.
You could use the same sensor in tank 1, then you need two 4-20mA converters at your controller. Presumably you don't need too much smarts in the controller. It's basically "fetch two tank levels" "if tank 2 is low, and tank 1 is not - run the pump" "if tank 2 is high or tank 1 is low or the pump has been running for a while - stop the pump".
You don't need a Pi for this. A simple micro and some LEDs would suffice. You can optionally export the tank levels and pump status out of a serial port for something else to log, and display on a nice web gui, but really, the less there is, the less there is to go wrong.
Statistics: Posted by ame — Sun Dec 21, 2025 7:36 am