...Another change that had occured with the hot weather was a dieoff of the pond weeds on the shore and about half of what was in the water.
I'm no aeration expert, but the die-off of aquatic vegetation is a huge red flag. Big time withdrawal on your oxygen bank account from the dying plants. Then the aerator kicks on and brings your very worst water off the bottom and mixes it into an already low DO system. I believe that's why they say to start up the aerators earlier in the year and let 'em run.
