Published on: May 15, 2019
Aeration is the process of adding oxygen to water. It is a key component to any pond owners’ success in keeping their ponds healthy and clean. Different types of bottom up and surface aeration systems work to infuse bodies of water with oxygen to improve pond health.
Adequate levels of oxygen are required to support life within the pond ecosystem. Fish need oxygen the same way we do, the main cause of fish kill in ponds is due to a lack of oxygen. Bacteria also require oxygen to allow respiration. Bacteria play a key role in ponds to break down organic matter in the water to reduce muck and sludge from settling on the bottom of ponds.
Fountains and bubblers are two types of surface aeration systems that work by agitating the surface of the pond to mix oxygen into the top layer of the water. Fountains pump water into the air, creating small droplets that collect oxygen from the atmosphere and fall back into the water. Bubblers or jets work in a similar way, by bubbling and mixing the surface of the water, catching air from the atmosphere and infusing it into the top layer of water.
Surface aeration will help control top level algae and weeds but they do not aerate down to the bottom of the pond where oxygen is needed most. Typically, water at the bottom of ponds is colder and contains less oxygen naturally, this is occurrence is called thermal stratification and it can put your fish at risk. If a pond is stratified fish will hang around the top layers of a pond where there is more oxygen. But, if a wind or rain storm occurs and the stratified water is mixed it can cause a mass fish kill because the destratification will mix the oxygenated water with the depleted bottom layers, lowering the overall oxygen content.
The bottom of ponds is also where dead organic matter such as weeds algae and other nutrient waste sink down to decay. If there is no oxygen at the bottom of the pond to support the bacteria breaking down waste, a build up of muck and sludge will occur and require costly dredging to remove.
You can see how surface aerators are an ineffective solution to keep ponds clean and healthy.
Bottom up Aeration systems are 5-10 times more effective than surface aeration. These systems work by compressing oxygen and pumping it into the water through diffusers that lie at the bottom of a pond, lake, or dugout. Small bubbles are diffused into the deepest section of the pond, and as they rise up the water column, oxygen is transferred across the surface of the bubbles and into the water. This achieves total pond aeration from the bottom, up to the top regardless of the depth of the water.
The bottom up motion mixes the water, reducing thermal stratification. Oxygen is equally dispersed at the bottom and top layers of the water which minimizes the risk of fish kill. The high oxygen levels support bacteria, providing them energy for respiration to consume decaying organic matter. This cleans the pond water, improving health and colour as well as reduces the amount of muck and sludge. Algae and weeds are also kept at bay.
Bottom up aeration systems are also less costly to operate than surface aeration. The power that it takes to pump water up is much more significant than what it takes to pump air down, causing surface aeration systems to cost 2-3 times more than bottom up aeration systems to operate. Bottom up aeration systems can also be powered by windmills, which are better for the environment and have zero operating costs, using only the power of the wind.
Studies have shown that bottom up aeration can have an oxygen transfer rate up to 10 times more than surface aeration. For example, at 10ft of water up to 16% of the oxygen diffused can be dissolved into the water using bottom up aeration; at 15ft over 20% can be dissolved. The oxygen transfer rate using surface aeration typically ranges between 1.6 and 3.2%
In conclusion, you can see below that bottom up aeration is the clear winner for treating ponds efficiently and effectively.