Lowrance Interference After Dark

I run a Lowrance Hook 7 for sonar only. I can have a perfect working sonar all day but when the sun goes down my screen looks like the below picture. I thought I was going crazy but this happened 4 nights in a row. Thoughts on what’s happening?
DT

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Clouds of zooplankton most likely

Yup, bugs coming off the bottom. You can try turning the sensitivity down some to get rid of some of the clutter. Using some of the clean modes/interference rejection may help a little too but I don’t play with that much.

I’ve had it so thick the unit struggles to read the true bottom depth.

Tucker

Just curious, does that lake your fishing have a good amount of perch. A couple of lakes I fish do the same thing.

I have had the same thing ice fishing. It does feel bizarre and frustrating. Like the others said I believe it’s some type of zooplankton or microscopic bug hatch

I believe its small bugs coming off the bottom too. as I mostly see it in soft bottom areas.

I cant see your frequency, but I am guessing it is 200kHz. When I see this crappie fishing around dusk I switch to 83kHz and it seems to poke through the fuzz better.