Hey yall i need a little info, i have a lowrance mark 5x pro it seems but be an ok unit for the price, im still learning to read it properly, ive read articles on thermo clines and other things to look for on a graph when searching for fish. for the last couple weeks ive been fishing a local lake in saline louisiana and ive noticed this line across my screen, ive fished 18 fow and this line appears around 9-12 feet if i move to 25 fow im still seeing this line in that depth range, could this be the "thermo cline"? or would my unit even pick this up. the perch im catching all seem to be right above this line...and i dont always see the line,just certain areas of the lake. i have my unit tuned fairly well as i can see my 1/16 oz jig and split shot while fishing under the trolling motor where the pick up is mounted, any info on learning to read some of these things would be very helpful and appreciated. trent