Single frequency VLF machines (Very Low Frequency) like the Ace 250, have limitations in the harsh saltwater environment. Take for example the Tesoro Lobo Super Traq. This VLF single frequency machine (17.9Khz) is one of the finest and deepest gold nugget finders on the market today. The Lobo Super Traq, is capable of finding BB-sized gold nuggets eight-inches deep in heavily mineralized ground, or a nickel in dry beach sand at 12-inches. Put that same nugget – or even the nickel, seven-inches deep in wet saltwater sand and the Lobo could walk right over it while chattering, or maybe without seeing it at all. Why?
The magnetic iron sands (“Black Sands”), salt, and high concentrations of other minerals in the water and sand conspire to bounce the radio waves away from the target. Conductivity and mineralization act like a shield around the target and create white noise that must be filtered electronically. Think of it as turning on your bright headlights in a heavy fog at night. All that powerful light is diffused and causes a complete white out – you can’t see anything three-feet past the hood of your car! However when you turn on your yellow fog lights, you can see a little further – not as far as you could in clear daylight, but further. That is why all radio wave machines must be “ground balanced” or tuned, to maximize their depth potential, and why BBS filters and multi-frequencies are so effective – yet still limited.
Unlike BBS (multi-frequency "Broad Band Spectrum) and single-frequency VLF metal detectors, which constantly send and receive thousands of low frequency sine waves per second, a Pulse Induction (PI) metal detector fires high-voltage pulses into the sand several hundred times per second. If no metal is present the electric pulse decays at a uniform rate with no anomalies. When metal is present a small “eddy” current flows through it causing the voltage decay time to increase, which creates a measurable anomaly. Unlike VLF radio waves, electronic pulses are impervious to the effects of conductivity and mineralization, and are unaffected by salt or black sands.
You need a multi-frequency or PI machine for best results in wet saltwater sand or saltwater.