The manual suggest a starting sens of 20 for salt water, so 19 seems right in the ballpark.
Also, you didn't mention the mode you were operating in.
Have you tried both of the Beach modes...which are specifically optimized for wet salt beaches?
(The 'optimization' part is specifically about reducing salt noise...especially Beach 2.)
Lowering sens to 20 or so does reduce some depth, but not as much as you'd think.
Running the sens too high, OTOH, will cause you miss many of the deeper whisper signals, as they'll disappear into the 'noise' chatter.
So running too high a sens can cause more depth loss than a little low.
Observing/finding optimum sweep speeds is a good thing to do. Note that the best sweep speed will change slightly with changes to recovery speed, and especially coil size.
(This is true with pretty much all detectors.)
Good luck, and have fun,
mike