My 9 year old son just bought an ACE 250 and we've been detecting at the local tot lots in the parks. I'm quite impressed with the depth on this machine as we've been finding coins at 5 or 6 inches deep. The problem is that while the bark is easy to dig, it tends to fall back into the hole when digging deep. You can widen the hole but that also creates a huge pile of bark to sift through. Maybe we just need more practice, but if you have any tips please post. Thx.