GW, Others - ".....but aren't you going to still make a significant difference if you aerate in the daylight hours? Wouldn't you be loading up on oxygen so that as it drops through the night it isn't likely to reach as low a point?"
As always, it all depends. Yes and No. One will probably make a significant difference by aerating during daylight primarly by mixing and adding DO to water depths that would not have had DO naturally due to lack of sunlight getting to the depths or those zones. All surface mixed and light receiving water (euphotic or photosynthetic zone) will usually become saturated with DO during sunlight hours. Unmixed zones of the deep waters and or dark zones have no DO additions once thermal stratification occurs.
But here is the kicker. Water at different temps will only hold so much DO until the water is 100% saturated. Super saturation does occur but the super saturated DO will be quickly lost into the air when the sup saturated water reaches the surface. As water warms the amount of oxygen it can hold DECREASES for it to become saturated. So in increasingly warmer waters the water actually holds less DO at the point of saturation for each increase in temp. Thus trying to supersaturate the water or "load it up" on oxygen beyond the point of 100% saturation does IMO little good. The amount of BOD (biological oxygen demand) of each water body and at each depth zone determines how long the DO will last during the non-photosynthesizing periods.
Last edited by Bill Cody; 06/28/08 02:33 PM.
