I finally got my Helix to show arches in 2D, found and caught fish with it today. Had to put it in max mode on the switchfire, and dial the sensitivity way down.

Now, here is my question. When I mark them on 2D, and side by side it with DI, is it a setting that I'm missing, if it just looks like plankton or trash all over the whole screen? I've taken the sensitivity down to 4, and it still there. If I go further, it pretty much takes everything off the screen. So many crisp pics from other people's DI, and mine constantly looks like a screen full of trashy water. Also, other than dock supports and bridge pilings, I get nothing on the SI. Also a settings issue?

Definitely a settings thing. Make sure you go into the setup tab and change the user mode to custom. This will give you some additional control over the settings. Then I suggest placing the unit in demo mode and experiment with your settings. Once you have it where you want it, go out on the water and you should be close. Just fine tune it according to the water clarity. You will have to do the same thing for SI. There are also several good youtube vids that go into detail regarding Helix settings.

Your unit doesn't have true Down Imaging from a Down Imaging piezo in the transducer. The unit has simulated DI views (composite DI) created by blending the two SI pulses. Anything you see on DI is SI so all the "clutter" is from not only what is under the transducer, it's from the side coverage of SI also.

Somewhere there must be a setting to clear it up. Ive seen plenty of images from others units, identical to mine without it though. Either that, or there is a problem with the transducer. Maybe that's why it doesn't mark fish in clear mode too, I don't know.

This is a MEGA unit, that doesn't have the actual down imaging either?

I have it in custom. Funny thing is, there is nothing even remotely close to that in DEMO mode. All images are crystal clear.