It was posted in another message about someone who saw bubbles coming off of
algae in their pond. I saw the same thing with some algae on the background
of a concrete aquarium that I have outside curing. I have also seen this in
planted aquariums where little bubbles were coming off of the leaves of
plants. This happens when the water is completely saturated with oxygen and
can not hold anymore of it. As the plants produce oxygen the oxygen can't
dissolve so it makes bubbles that float to the top. Yesterday I tested my
concrete tank where there were oxygen bubbles coming off of the algae. Sure
enough the oxygen was at saturation point.

With that said take a look at your algae in the sunlight and see if it's
producing bubbles to see if your O2 levels are high. If they are and your
water is under 95 degrees your pond is providing enough oxygen for your
fish. At night though your oxygen levels will go down. I'd measure your
oxygen levels with an O2 kit in the morning to make sure you are ok all
around.

Sam