Looks like the MT6 is a uselss piece of equimpment in Florida for 6+ months of the year
straight from the manufacturer:
The specifications on the data sheet state the MT6’s operating temperature only goes up to 120 degrees. If the temperature is higher than that, we cannot guarantee its accuracy.
In regards to the nails, 6" is the deepest the tool will be able to pick up metals. If your nail heads are close to or below that 6" depth, the tool may not even register them.
Your situations seem to be pushing the limits of the tool’s capabilities. I wish I could give you more exact data about how the tool will react, but it is hard to determining whether or not your situation is too much for the tool. If you have any more questions, please contact us again.