Bottom Clutter on Lowrance 510C

[MNBIGBEAR]

I am having some type of issue with my Lowrance 510c showing an unusual amount of bottom clutter/interference in the bottom 3-4 feet on the screen. Not sure if it is just a coincidence or not but it seems low-light times it gets worse. The middle of the water column is crystal clear. I can usually still pick fish arches out among the clutter but definitely seems odd. Any suggestions or explanations? Thanks.

[CaptainMusky]

What do you have your sensitivity set to? Is it on auto or manual?

It is entirely possible it is a hatch of some sort, what is the bottom content where you notice this? Softer bottom would make me lean toward a bug hatch. If its in all areas regardless of bottom type then it could be a variety of different things, baitfish, etc.

[delcecchi]

zooplankton and phytoplankton come off the bottom at twilight. If it is always there, even in mid day over rock then that isn't it.

[Kyhl]

How deep is the bottom clutter? Years ago on an old X55 it would show the thermocline as clutter. The clutter would stay fairly level while the bottom depths changed.

At least I assumed it was the thermalcline.

[MNBIGBEAR]

I have noticed it more in soft bottom areas in depths of 15-30ft of water. The phytoplankton explanation would make sense with it being more noticeable in the evening. I dont believe it is showing the thermocline as it follows the contour of the bottom in a relatively uniform 2-4 ft band. Thanks for the input guys!