I have been using the Explorer at a park (I live in West Michigan very near Lake Michigan) and encounter a lot of nulling--where I have to sit and wait for like 5 seconds for the threshold to come back. I'm running across big patches of ground where this happens. The area is an oak woods with about 2-3 inches of dry silty dirt on top of heavy orange sand, so I'm wondering if it is iron in the sand that makes it null out. I don't find many nails or scrap iron here to speak of, but there are a lot of huge low ferrous signals. Increasing iron mask makes it null more, so I guess the thing to do is run it in almost all metal maybe? Just wondering if anyone had ever experienced anything like this or had any advice.