My Elite 5 DSI was picking up the same grainy image from 0-10' down ... when fishing Watts Bar Lake in E Tenn. (a week ago), and the water clarity was clear to over 3ft down. Saw some of the same image blurring at a local lake, just the other day. Not everywhere, and not down to 10', but still present off & on.

I thought it might be a big temp difference, kinda like how the thermocline shows as a grainy line across the screen ... with the very warm (60+degree) water suspended over much colder water ... so I didn't bother to take a screenshot.

... cp