FFS Image - Need help

[One Trick Pony]

I am getting this weird half moon shaped ring now that there is considerable algae suspended in the water. Is the algae the likely cause?

I’ve tried going to a 20 degree angle vs 40 degrees and turning the sensitivity down to only 3 or 4 but I am still getting it. Played with contrast too but nothing seems to help.

What causes the half moon effect and how can I eliminate it?

Thanks for your help.

[Wayne P.]

Hard bottom and high Sensitivity.

Algae and thermocline will be foggy looking:

[One Trick Pony]

Hard bottom for sure Wayne, but I turned sensitivity down to 3 and still have it.

I’d go as low as 1 on the sensitivity but won’t that affect fish detection?

[SLYDoggie]

I moved this post from the Image Interpretation forum to this forum... better place for this type of question.

[RyanJ]

I get that same arc looking image at times. Have not been able to figure out why it's there.

[Wayne P.]

You will get the most semi-circle affect in Down mode
It is a product of the technology. I have seen the same posted on a Lowrance forum.

[JohnN]

I get the same thing intermittently. Try adjusting the transducer angle.

Edit: I see you tried that already - sorry. This has helped eliminate it for me in some cases, at least.

[Avanti]

The distance of the return makes me wonder if trimming up the motor might eliminate it.