Hey Easy,
According to Dick Pool's Downrigger book somewhere between 0.6 and 0.7 is ideal for salmon although it differs by type of salmon. I think the natural electrical current generated by the reaction of your zincs with the stainless wire is somewhere around 7 or 7.2. If you have a grounding problem you could have charge of less than this or even negative. My boat was "hot" before I added the box and ran somewhere around 8.9 on the electric meter. Most the people I talked to thought this was probably scaring fish away instead of attracting them.
JMS