Need some clarification...

[exnavyguy]

By turning up the sensitivity on my ACE 250, does that allow the machine to search deeper or does it just allow for the machine to pick up more items that maybe I could not find when the sensitivity was turned down. I ask because the school yard appears to be empty and I can search thirty minutes or more without finding as much as a pop top or nail unless I turn the sensitivity up. Hopefully that is not to confusing. Thanks

[LaRoper]

Yes, the sensitivity will push the detecting range deeper. This works great in low trash/iron areas, like the one you are talking about. Allways try to push your sensitivity as high as you can, too high will make the detector unstable and could mask good targets next to bad targets.
Also try the all metal mode and use you target ID meter. Anything above foil I would dig.
Hope this helps.
LR