I do not feel that you can turn the pond over too much (after steady-state operations has been met)unless it causes super heating or cooling, as mentioned.
I have been running from 9pm to 9am, but this last weekend was so much cooler I ran 24/7 and the only thing I noticed was a slight reduction in feeding enthusiasm and the clarity dropped from 22" to 16". I had noticed earlier in the year that the fish did not feed as well with the air on, but it may have some to do with it being before 9am as well. Before the increase in runtime, the clarity was worse in the morning, but improved by a few inches by evening because the diffusers were not constantly stirring the pond up. I have heard that a pond with 24/7 aeration will clear up eventually, but mine was started in the heat of the summer and I have not seen that happen. So, the only thing that I am watching for are pros and/or cons of turning the pond over up to 8.5 times a day, per my estimates.
A few things that I think about that relate to running the aeration more than a few turnovers a day are...
1.) What does the muddier water do to the pond? Muddy ponds tend to have less colorful fish. Feeding seems to be less aggressive. Everyone likes a clear pond, but clear water has it's problems too, usually related to fertility. I think a muddier pond acts like dye and should reduce FA and deeper plant life.
2.) I can't help but think that the DO2 is maximized the more the pond is turned over and I do not think that I am reaching saturation only running 12 hours a night, if saturation is even possible.
The nice thing about having some "extra" turnover power is that I can turn the system UP when a cold rain is coming so that it mixes as it rains rather than washing in and turning the pond over and the muddiness of the water during this time washes out the pipe above full pool carrying some sediments with it. I do not believe these concepts are real game changers, just thinking out loud so take with a table spoon of sugar.
