I have found that on some wet salt sand beaches, the AT Pro did NOT want to ground balance because of extreme Black Sand and highly mineralized sand and salt .... .....while on others , the G.B; was no problem ......You will see the numbers drop down from about 20 or so on down when G.Balancing in the wet salt sand .... You may also have to turn you sensitivity down ......>When trasitioning from wet to dry , your AT will tell you by the noise it makes that it's time to do another G.B. !!... Dry sand G.B. well and it runs quiet and DEEP !!.. This is what I bought my AT Pro for .....I can fly down the dry beach wtih this machine and hear targets all the time ...... This machine LOVES dry sand !!......Jim
Noticed too that in the water where the AT could not be G. Balanced that the water running over the coil was pretty noisy too , but that is to be expected .....I didn't have my boots the day I had it on the beach that was easier to G.B on ........I hope it quiets down .....No matter ....I was resigned to the fact that all I really wanted it for was a dry sand machine , so anything more I get out of it is a bonus to me .......Jim