I am prototyping with small scale generators and I keep getting a layer of green sluge floating on the water. I am using salt as the electrolyte, 5 steel nails as nodes, 2+, 3- connected woth copper wire. The power source is a 12V 18Amp car battery. My first thought was that the sluge was a byproduct of the copper oxidizing but there is little evidence of it on the wire. Any help is appreciated. Thanks!