ACE 250 on the Beach???

is it a salt water beach or fresh?
if it's salt, you'll likely get some falsing as you get closer to the wet sand/water. just start detecting in the dry sand and work your way towards the wet sand and you'll probably get to a point where the falsing begins. turn your sensitivity down until the false signals stop.
different beaches also give different results. i've been able to run my 250 at 6 on the sens on one beach with no problem, while on others i have to lower it to 3 or 4. and i usually run in all metal mode and i only have the stock coil.

i do find when i'm getting the false signals, the target ID will jump around a lot, but the signals are usually somewhere mid-range (but jumpy mid-range) and those signals will almost always show initially as being 6 inches deep and then the depth will get jumpy along with the ID. and even though the coil is waterproof, i generally try to keep it out of the water for the most part.
i've even had false signals from blobs of wet seaweed near the high tide mark. that stuff holds the water and it's high in minerals.

Pete

It is for a salt water beach.

I had a co-workers old old Tesoro that half worked when I was at the same beach in September. I couldn't get any discrimination to work with it and was stuck on the dry sand.

Take a pinpointer. I was surprised how much I used my propointer at the beach.
Wet sand doesn't sift out my scoop.

Yeah, I'll definitely be taking my ProPointer. =D 4 more days till I get down there. I'll be visiting a few local places till then just to pass the time. Feel lucky that we are having this warm of weather in PA.