I have been told that sonar will not mark fish or structure well in less than 20 feet of water regardless of how nice the unit is. What are you guys thoughts on this? One lake that I fish in a lot is a steam plant lake with average depths of around 10 feet. Will it only be able to show me depth or can I fine tune it to show other fish/structure? Right now I am running a Lowrance X-96. Thanks for the input!