Depending on where you hunt 20 may be way too high. Too many people think you have to run max sensitivity to find anything and that is total bunk. Even with sense at 10 you will find plenty of good targets. On many areas I run down around 16 to get rid of the chatter and I can still hit a dime over 8". Depth is very overrated unless you are cache hunting. Most coins I have found in fifty years of detecting have been in the top 6" of soil in undisturbed soil (no landscaping or silting in from floods). The problem with high sensitivity and chatter is that although you may get a small bit more depth you will be more likely to miss a good signal in all the chatter. Turn the sense down until the chatter disappears and all the good signals stand out which will result in a better recovery ratio. In the woods where there is little trash in the ground I can run pretty high, but in most parks and public areas, even private houses I have to turn it down to 16-18. Don't forget to noise cancel. Ground balance should not be necessary if you have mild soil but most do it anyways.