What Is Wrong With My Fish Finder?

[Unknownwaters]

Whenever I go to the deeper part of the lake I fish my fish finder starts picking up all kinds of weak readings throughout the water column

I tried turning the sensitivity all the way down, but there is still some wierd stuff appearing on the bottom

A few more photos of these weird readings.

I only get these readings in the deeper part of the lake, and my fish finder does not have a problem on other lakes that are just as deep. My best guess is that it has something to do with the fall turnover, perhaps abunch of debri was sucked into the bottom of the lake when the water turned over. Its my first fish finder, so I am still learning how to properly read it. its a Humminbird 596c HD DI

[wnybassman]

I had a very similar experience this year with my Humminbird 798. It was only on one lake, and it was only in depths of 35 feet or deeper. Every time I got to this depth, the bottom looked like it was loaded with bait. I didn't know what to think of it. Wasn't interference with the other graph, because it happened when the trolling motor was out of the water. Fall turnover wasn't an issue, because it was mid September. Mine looked much like the third picture you posted. It is a lake I don't visit much, so I'm not sure when I'll get to experience it again.

[Wayne P.]

You two should do a Google search for "thermocline"

[wnybassman]

You two should do a Google search for "thermocline"

I was thinking thermocline, too. I just never have seen one laying right on the bottom like that. All of the ones I have seen were 2/3rds of the way down or so. Makes sense though, it's the time of year one would set up around here.

[Unknownwaters]

You two should do a Google search for "thermocline"

I guess I never expected the thermocline to still mess with my fish finder even when I have it on the lowest sensitivity and switchfire in clear mode. Nor did I expect it to cause weak signals throughout almost the entire water column like it did in the top photo.

And is it suppose to show up on DI as well?

[Wayne P.]

I always have my units on Switchfire Clear. That has enough sensitiity to show anything I want to see.

If you notice on the right side of the image, the thermocline is on the bottom and was like that for 50 or so yards until it got shallower.

This is another thermocline at the bottom on another lake. I just was checking where it was and wasn't interested in water deeper than that.

[Unknownwaters]

huh, interesting. Thanks for the help

[Wayne P.]

This shows a creek channel that is below the thernocline in this area. That shows me that I don't want to fish that channel edge at that depth:

[SoFlaBassAddict]

I swear. Wayne, you've got some fantastic screenshots saved.