The way its done is to auto GB and once you have that done you go back in manual mode and start to drop it by 5s till you start to hear ground chatter and then you back it up by 5. By doing so all it does is turn the ATP a little "hotter" to finding any item not just silver however when you do find silver it will scream. I have done this since I got my new ATP and I get crazy depths from it. Just don't go nuts thinking the lower you go the better because you will end up knocking making it work against you, don't go more than 20, I usually go about 15 and I get targets an easy foot deep and see it displayed on screen not just hearing it. hope this helps