Hello to all,i am New to the site and nice to meet u all,i have a Garrett 2500 (2007 model),got it out and have been using it but i Believe i got mayb some problems mayb not,,,i took it to a Lake where they swim to try my luck out,well ever time i got near the ground it overloaded,there was alot of black sand and the bank was moist,i got it home and started testing it,it will overload on a 50-cent piece if i hold it right on top of it,if i lift off it works fine??? i have reset to factory programs and using Dis/coins mod. im new to the 2500 so is it me? how do i metal detect the lake area with all that black sand? Thanks so much eric