In my Excal freshwater experience, you can often go full tilt on sensitivity...after all, it's the salt that's the main challenge to most machines, and even in saltwater, I go with zero disc, although you may choose to use just a bit, if you're having trouble with foil or some other low conductivity stuff......'course just remember that gold lurks down there as well. A big gold band can sound nearly like a penny, but small, irregular gold items get lower and quirkier, the more irregular they get. Most detectors love circles the best....making a break in that circle is what makes it tough to broken gold rings, gold toe rings and, of course, gold necklaces and chains are one of the biggest challenges. The machine tries to see each link, so small stuff is REALLY tough....without a pendant or something similar attached, a large percentage of detectors out there will miss small necklaces. Fortunately, i have another tool in my arsenal to tackle those........