Right voltage for downrigger?

[Finntroller]

Hi,#13;#10;#13;#10;I'm asking what will be the right voltage for zander/pike-perch in clear water lakes? I'm using blackbox with downriggers. 0,700 volts works with trouts and lake-salmon here. 0,600 volts works sometimes with zanders, but does anyone know more?#13;#10;#13;#10;Best regards from Finland Europa