Tell you the truth, I will swap out to the 6" coil first before running any program with discrimination. The CTX does quite well in trashy areas especially with it running in "High Trash" Combined mode that I still don't bother with any discrimination. Reduce the coil size and you can get even better separation, it sees less minerals, allows for higher Manual sensitivity, thus possibly reading deeper than the 11" in the same soil.
Example.... A little over a week ago, I popped a near perfect 1942 Merc right at 6" deep with the 6" coil that rang up loud and clear running in Manual at 26-27. Followed by four deep Wheaties at 5-6". I tried the same area first with the 11" coil and it was picking up too much of the ground minerals per swing causing it to false annoyingly on anything above 21 in Manual to give me reliable tones. Thus why I swapped for the 6" coil. Granted this was just a curb line, and not a huge park or field. I love that little dirt sniffer!
Example.... A little over a week ago, I popped a near perfect 1942 Merc right at 6" deep with the 6" coil that rang up loud and clear running in Manual at 26-27. Followed by four deep Wheaties at 5-6". I tried the same area first with the 11" coil and it was picking up too much of the ground minerals per swing causing it to false annoyingly on anything above 21 in Manual to give me reliable tones. Thus why I swapped for the 6" coil. Granted this was just a curb line, and not a huge park or field. I love that little dirt sniffer!