Detecting water level and pumping it out

Okay, so i'm all out of ideas. I live on a boat, which sadly leaks. Not very much, only about 50 litres per 24h. We collect this water in a 8 litre tank, which is the biggest one we can fit. We want this tank to empty itself. For this purpose we have installed an electric pump which runs from a relay. The relay is controlled by two switches, one in the top of the tank, and one at the bottom, When the top switch is closed, the relay activates and keeps itself opened until the bottom switch opens again. This runs on 12v. In theory. In practice, i make some hydrogen gas (i think) and consume about two amps.

The problem is that my "switches" are two copper wires that are supposed to be connected by the water when it rises, but this doesnt seem to work. When i put voltage on the wires, they consume ca 2 amps and create lots of bubbles. I can get ca 40 mA through the water and into the relay, but this is not enough to turn it on. Im considering amplifying the signal with transistors, but cant get hold of any here in cape verde. I also wouldnt know what kind of transistor Id need.

I have tried building switches that connect wires when a cork floats up in a tube, but they are unreliable, especially when the boat rocks.

Does anyone have an idea of how i can build a "no moving parts" switch or in another way solve this problem? Id be very grateful for any ideas!

 

That makes sense, of course. less corrosion would mean lower resistance over the gap aswell i assume. I will try with stainless electrodes and meassure how much current i can get through then. hopefully that will be enough to open the relay, but well see. Why do you ask about guitarr strings? i actually have a recently broken guitarrstring onboard so i could use that for electrodes.

That was exactly the kind of information that is very obvious, but still hard to find when you dont know that it exists. So even with copper wires i should be able to fix this with darlington transistors.

That would work to. Can microswitches usually be found in electronics?

Worst case scenario we will have to fix this in the caribbean where ill be able to buy more things, but hopefully trying different electrodes might do the trick, in combination with some transistors i might find in an old navtex receiver that we have onboard.

Thanks for your help.

 

That would propably work aswell, but its not ideal because the leakage differs with rudder usage. Thus when we are in port, we sometimes dont leak at all. Its also the problem with not being able to order anything online as we are constantly moving. Its still not a bad idea though, to check the exhaust for the close signal. I will think on it.