Looking at the Nox 800. In beach 1 & 2 how many of the five frequencies are being utilized. A while back I saw a utube video of a gold chain in shallow saltwater that the 800 identified but the other machine could not. Is that because the 5,10,15,20 and 40 Khz are working together or are only three or four frequencies being utilized in beach 1 & 2?