This is my second season using the FL-18 and I've noticed a few things on reading hard and soft bottoms. If I notice a wide and bright red area, with very little orange or green after it, it is a harder bottom. If it is less bright and a narrower red area with alot of orange and green after it is softer. One note about checking the bottom hardness is you can't play with the gain or it will mess up your comparisons. Good luck !