On a side note, the boil attracts BG which in turn attracts the pond predators. In the evening when I am feeding, I will notice quite a bit of activity around the boil. LMB sometimes leaving the water in pursuit of a meal. I have also caught all sized BG with my flyrod by tossing grasshopper flies around the boil.
In my old pond, the shiners would school up in the bubbles. Late evenings, they would all go airborn simultaneously to escape the bass.
