Hi Otto,
The Deepstar was developed primarily for beach detecting and ground balancing is rarely needed. Only on beaches where the sand is derived from volcanic basalt would you need ground balancing. Even then, some magnetic sands do not give a signal with PI. It all depends on the particular iron mineral present. Salt water beaches are heavily mineralised due to the conductivity of sea water, but this type of mineralisation causes little problem with PI and no separate ground control is needed. I used to make a PI detector called the Goldscan that had a ground balance control but that has been out of production now for about five years. The Minelab SD series are the only PI detectors that currently have ground balancing as their primary application is for gold prospecting in highly iron mineralised inland areas.
Eric.
