I know there are driffent threads on the subject, though most of them seems quite complex especially for one who does not know a lot about electronics. I want something that will switch on a solonid that will lift the check valve of its seat in the feed water pump, when the water level are at the right level. Does anyone know how to make sensor like this? Maybe I can have two electrodes close together and energize one of them, so when the water touch it will pass the current to the other electrode? /Jim H.