VLF detectors are "small gold" dead in salt water, wet salt sand. Salt is a mineral, mix it up with water and it becomes conductive. Ground balance adjustments and different coils can be configured to battle mineralization. Any adjustments for conductivity issues and it becomes "small gold dead" in wet salt sand/salt water. Garrett responded to questions I also had with this:
"Thank you for your purchase of Garrett products. We are happy that you`re pleased with your AT Pro. In order to get the best performance in your salt water beach environment , Garrett suggests you use a PI detector ( pulse induction ) instead of a VLF detector. As mentioned in the owner`s manual , the saltwater environment is challenging for any Continuous Wave (VLF) detector, and the Garrett engineers have developed the best state of the art machine available on the market today designed to deal with these conditions. It is a very effective tool for this application however , adverse conditions may dictate ( if necessary ) the need to notch out the pixel under foil thus allowing a reduction to some items. To better address your questions , I have forwarded your requests to our Marketing and our Engineering depts. Please remain patient as we wait for their response.
Best regards"
These three statements caught my attention -
1. "In order to get the best performance in your salt water beach environment , Garrett suggests you use a PI detector ( pulse induction ) instead of a VLF detector."
2. "the saltwater environment is challenging for any Continuous Wave (VLF) detector"
3. "adverse conditions may dictate ( if necessary ) the need to notch out the pixel under foil thus allowing a reduction to some items."
Tie a string on a gold ring (or anything considered "small gold") and bury it down a bit in the wet sand right at the water's edge. Please report back the results. If you are serious about hunting for gold jewelry in those conditions found at salt water beaches, according to Garrett, a pulse induction detector is what they recommend. In dry sand, the AT Pro is a great machine to use. Good luck and happy hunting.