Its tough to disc out those bottlecaps...actually not a good idea for a water hunter anyway...I hit a big 12gr 18k/Plat Artcarved one year that sounded just like a bottlecap....
Fresh Water Wading, the AtPro has about the best reputation and capability for the money...then the scoop at @$150 lets say...So you are into it with the basics for lets say $750...Then waders or a wetsuit if you need them....so lets say close to $1000 all in...
That means you really gotta be committed and work the right locations to pay the gear off ASAP, that means gold/plat/chains...Good thing is the scoop and Pro hold a decent resale value in case You dont enjoy water hunting....
If you are going deeper than wading, thats a whole nother ballgame there...Huge barrier of Entry from a financial/fitness angle.....easy $4k just for starters...(Dee could chime in here for accuracy on the estimate)...
Not a bad idea though, if a guy is so inclined...probably the Final Frontier of Detectordom will be diving to hunt for old swim rafts sites, jump off cliffs, etc.....Thats some super strenuous work though, to go subsurface and geezle around in zero vis...let alone all the gear weighs a ton....
The AtPro hits fresh water gold like a frigging TRAIN! Right out of the box with the stock 8x11 Even.....It can see chains too, so theres that to consider.....My best find so far was a 2 1/2oz 999 gold chain that sounded like a pair of pulltabs....AtPro...Stock 8x11 coil...just wading along one fine morning....