Dennis has given you some good advice on the Sand Shark. As well, I would like to add a few things.
I bought my Sand Shark years ago to detect nuggets in insane bedrock where VLF's just could not ground balance. The Sand Shark has a processor that operates to ignore harsh ground mineralization, especially salt and high concentrations of black sand, and the pulse induction feature completely ignored the mineralization in that awful bedrock I've referred to. However, as Dennis has stated, the Sand Shark will not find small gold. Nevertheless, when I got a signal with the Shark, I knew it was metal, and the bedrock I was hunting was not littered with trash, so I also knew it was going to be a meaty nugget, nothing tiny.
There were two types of bedrock it excelled on. One was a red bedrock that was hiding nuggets from VLF's and the other was a black bedrock with lots of graphite and other minerals that completely overwhelmed VLF's. The Shark ran nice and quiet over both until I got the coil over a target, and I liked that simplicity.
Compared to today's modern PI's with intricate ground balance, and numerous settings designed to allow detection of small gold with a wide range of coils designed as well to assist in sniffing out that small gold, the Shark is just not a contender. However, when I ordered it, PI's were still in their early stages of birthing, and the Minelab 2100 had just come out. The 2100 also handled the mineralization and produced a lot of nuggets on that bedrock for me, but at that time, it would not find small gold either as there were no sensitive small coils developed then. As the Shark was far, far lighter than the 2100, it was a pleasure to swing it compared to the beefy Minelab.
I've used the Sand Shark for sniping bedrock after I've dredged clean a section of bedrock, and it will find the gold in the bedrock, but once again, nothing small.
I ordered it specifically to do a job for me on insane bedrock that completely ate VLF's right up! It will still find nuggets as long as they're nothing tiny, and there are a range of coils for it now. Regardless, now that I have a highly dedicated gold-finding pulse machine with a wide range of coils and micro-processor settings, the only time I use the Shark for chasing nuggets is underwater on bad bedrock where a modern VLF won't operate.
All the best,
Lanny
