I think I have my LX3 just about figured out. You have the correct setting for your depth, are you fishing in weeds, that may cause you to loose sight of your jig when you get close to the bottom? The gain should just be turned high enough to see your jig, any higher and you will get a lot of interference. I have never had my higher than 2. On zoom, your are correct, when the 2 lines hit the bottom of your view, the picture on the left will be the bottom 5 feet, the whole water column will still appear on the right. As for the IR, I don't know how close another unit needs to be to cause interference? I don't recall seeing the flashes on the left when in the zoom mode? Sorry I'm not much help here. There is a good tutorial in Youtube, just search Marcum.