Once you've gotten the pond broken in, I highly suggest you take temperature readings from top to bottom. If you can create a thermocline under your diffuser, great! If there is no thermocline, then once the top and bottom temps match or get real close, then you can back off on run time until those temp differences start getting bigger. What I'm saying is, why run your pump 24/7 if 6 hours gives you a complete turnover and saturates the pond with DO. The remaining 18 hours let's the depths cool and creates a deep, inhabitable haven from the heat and you're not overworking your pump, or burning electricity.
Elaborate? I thought the point of aeration was to NOT have thermocline?
There are two schools of thought regarding thermocline. The first is that since thermocline exists naturally in large, deep BOWs that maybe they should also exist in a pond. To do what they are intended to do, to provide an anaerobic area in water for decomposition. A body of water's natural process is to fill with sediment and eventually cease to exist. It also provides a cooler area where fish can escape to when temperatures become too stressful. They cant live down there, because it is virtually void of oxygen, but they can visit the area to destress. When using a depth/fish finder, if you have the sensitivity set correctly, you will see the thermocline on the graph, as well as fish holding right on the ceiling of it.
The second school of thought is that by eliminating the thermocline in a BOW, you convert the anaerobic process into an aerobic process. By infusing DO into every layer of water right down to the bottom. This process helps to reduce the buildup of muck by helping bacteria to break down the organic material, and eventually be displaced through gases as its brought to the surface. The stocking of fish that feed on detritus also helps to reduce the organic solids since now they, and all your other fish have full use of the pond. The trick in this thinking is having almost constant knowledge of the pond's water temps and adjusting run times to prevent super heating the entire pond. If your pond is off site, and you cant visit it often and make necessary adjustments, you could likely drive up on a pond full of dead fish.
The depth/layout of your pond, and the placement of diffusers will determine whether you can fully aerate the entire BOW. Elevated diffusers tend to leave a couple feet of dead water (thermocline) under them, unless you remove the bottom plate, which allows water to flow up thru the diffusers range of lift from below it, bringing detritus up with it.
Ponds set up to maintain a thermocline tend to be clearer, whereas ponds without a thermocline tend to be more turbid.
That's the way I understand it, anyway. If I missed something, or are off base, I'm sure someone will correct my misunderstanding.
