One thing to keep in mind when it comes to aeration. It is easy to be mislead to think that when we switch the air pump on we are starting aeration and increasing DO. Keep in mind that the bubbles themselves are only infusing a minute amount of DO. When we flip the switch on the pump motor what we are really doing is moving water.
Specifically we are moving lower water in the pond to the surface. It is this surface interaction that increases the DO for the most part as far as the water movement is concerned and if it is daylight hours algae is causing a lot more DO in the water than the air/water interface at the surface.
So when we flip that switch on and the motor hums are we increasing DO? Yes in the aggregate for the entire BOW we would. But would we be increasing it where the fish need it at that particular moment? I think it depends.
Disclaimer: I'm no expert and have lots more questions than answers. These are my thoughts not to be confused with actual good information. Keep that in mind as you read.
So when you flip that switch and start pumping water from depths to the surface the water that hits the surface infuses DO. But is that water on the bottom of the pond already sufficient with DO for the fish? Or is it deficient in DO? I think it depends on a lot of things. If adequate aeration was done at some earlier point where the lower water is still in good DO shape maybe that lower water is not too deficient in DO. But what if it is almost devoid of DO?
There are still questions in my mind if pumping water only during night hours is a good thing. I would think that pumping during some daylight hours where algae has a chance to mix with the water coming from the bottom and give that a quicker DO boost would be desirable. I would think that circulating some of that super saturated DO daylight surface water down into the lower regions of the pond to infuse it with DO to provide a DO "sink" would be desirable.
Rantings of someone that has a lot more questions than answers. For what it is worth I am running my pump from about 3am to noon and 5 to 8 pm. Trying to avoid the hottest part of the day yet circulate water while DO infusion by algae is still high.
Edit: It is my contention that from a DO standpoint pumping nutrient rich lower water up to the surface and mixing it with algae laden water would infuse much more DO in the BOW than pumping at night when the algae is dormant. But that does not address the problem of overheating the water.
Last edited by snrub; 08/23/18 10:25 PM.
