Hi Raul
I know that my wiki is somehow difficult to understand and that description of Sensor Server features is cryptic and obscure!
I have tried my best but I am not very good on explanations!
I believe that SensorServer is a very powerful code and have hundreds of potential utilisations. but it may not be so user friendly and detail explanations very every application is very time consuming!
I look forward to find some help and to get people , like you , involved on using the code and find possible examples!
Coming to your application:
In the attachment you can see how I understand your needs!
Sensor 1 measure level of Tank 1 and send commands to Sensor2 that control a Pump to fill Tank1 from Tank2.
Note : all area must be WiFi covered ( you can use any external WiFi repeater like TP-LINK CP210).
I assume you can install sensor1 in top of tank1, since a ultrasonic sensor is used to measure the water surface distance, and that you have power lines for all units. Sensor 2 can be mounted on top of tank2 (if you want to measure level of tank2) or everywhere near to the pump,since it will be controlled by a relay of Sensor2.
If this is correct , I can send you schematics of the 2 SensorServer units and a components list.
I will also tell you how to customise the SW for you application.
paolo