Pond Boss Forums AERATION Should I aerate? Aeration, muck, and thermal refuge

Just want to add a little additional context. The oxygen cycle where it comes to plants isn't always just a net positive of oxygen. For there to be a net positive contribution to DO, the plants need to be increasing in weight. This sequestration of CO2 results in net positive contribution of O2 but one cannot depend entirely on plants for O2. They usually reach a limiting weight and then the net is zero. If the standing weight of living plants declines, this can result in a net negative production of O2 because of the oxygen demand of decomposition of the dead plant material. But it does depend on the rate of decomposition the dead plants. Where muck is accumulating in O2 depleted water, the rate of consumption is often less than the production of O2 by living and growing plants that remain. Essentially, this is how the Earth itself became oxygenated. Dead materials were prevented from decaying and that is how the Earth accumulated O2. Still, DO diffuses to the bottom and so DO from upper layers is slowly consumed by decomposition taking on the pond bottom. The evidence of the diffusion is the gradient of DO that is observed where DO is lowest at the pond bottom.

There is a daily cycle of O2 that plants directly cause. During the day, plants accumulate photosynthesized sugars which contained energy is used to fuel metabolism and growth. Metabolism and growth continue in the dark and during this time oxygen is used by the plants to extract energy from the sugar. They consume oxygen they produced during daylight at night. But so long as there is net gain in the energy contained of the standing weight of plants, there is a net contribution of O2 by plants over the course of the entire day.

Absorption of atmospheric oxygen is important to DO. Aeration enhances absorption by bringing depleted water to the surface (whose affinity for absorption is greater than saturated water) and by disturbing the surface tension (something that elevates the time rate of absorption. Atmospheric oxygen is essential to the health of water and its inhabitants. Plants in the water will not be sufficient to produce the needed DO all the time ... though they may be part of the time.

Generally, water with high nutrients and high standing weights of plants have higher oxygen demand and more problems with DO. The more plants one has (whether blooms of phytoplankton or vascular plants) the greater the need for efficient absorption of atmospheric O2. The greater the need for aeration. Aeration will accelerate decomposition of organics that accumulate on the pond bottom. In as much as that is true, aeration increases the demand for O2 ... but this is supplied by the aeration itself where the source is atmospheric oxygen.