Tom, you are absolutley right. I didn't want to get into that in my original post but I also check the change in temperatures to get the probable location of the thermocline. HOWEVER, over the years I have been doing this, I have found that it is much easier to see the drop in oxygen content then the drop in temprature. Both ways are correct and will help to eliminate a lot of unproductive water by not fishing deeper than thermocline/depleted oxygen depts. As Peter said, "To know where fish will not be is huge."

Grumpy