Hi all, we have a large pond which we think is leaking;seems to be loosing more than evaporation. It holds approx 500,000 litres & is plastic lined (industrial reservour stuff) Question, is there a gismo that I can buy,borrow or bodge that will tell me where the leak is? I was thinking along the lines of resistance test between water (full of fish so no high volts) & surrounding soil;resistance would be lower where hole in liner & soil probe were close & closer would give lower reading. Help would be great, it's an awful lot of buckets to empty,regards Bob.