Correct the top 3 measurements are from 6 PM last night and the bottom 2 are from 6 AM this morning. I did not take a temperature reading but I would guess the surface has to be in the mid 80's. I'll get a temperature reading tonight. High temp for us today will be 97.

I was shocked that the 1/2HP surface aerator doesn't seem to be making much of an improvement to the situation. I would think at least the water near the aerator would show an acceptable level of DO. As soon as I powered on the surface aerator I noticed the water felt cooler around the surface aerator. I assume its pulling enough water from depth to the surface to mix with the warmer surface water.

Not sure how I would shade the pond, and during the day when the pond gets sunlight it seems to have a positive impact on the DO.

I too am concerned with the decaying plant matter. If I was to treat the pond again I guess I would only do around 25% at a time, but even at that rate I would be concerned something like this could happen again. I am surprised that it took almost a month after my second application of Reward to have any issues. I would have thought something like this would have occurred closer to application time and hopefully before a got to the second application.

Would adding another 1 HP of surface aeration be recommended? Is there a formula to calculate how much aeration is needed, something like X hp per acre for an additional X ppm of DO?