Bottom Aeration
This aeration system places diffusers at the lake or pond bottom which work to circulate the oxygen and water through the entire lake. This system is most effective in bodies of water over 6 feet deep. This is the most efficient system for pond and lakes that have a depth of 8 feet or more as it can circulate the entire water volume every 13 hours and has the ability to break the thermocline.
The science behind water aeration
Aeration Benefits
How does aeration have all these benefits?
Aeration reduces pond sludge:
- Increase fish habitat - Yes, rainbow trout can live throughout depths of pond if water is aerated. (It is a myth that trout cannot live in ponds that are aerated down to the bottom).
- Cleans water supplies
- Eliminates or reduces smells caused by anaerobic bacteria such as hydrogen sulfide and methane gases
- Reduces algae through the reduction of nutrients & phosphates
- Reduce heavy metals (manganese, iron, magnesium)
- Reduce ecoli
How does aeration have all these benefits?
Aeration reduces pond sludge:
- Pond sludge is the accumulation of nutrients over time. Aeration provides enough oxygen and water circulation for aerobic bacteria to thrive, and these bacteria consume these built up nutrients and therefore minimize and eliminate sludge build up.
- Fish need oxygenated water to survive, yet during certain times of the year oxygen levels can approach lethally low limits. Aeration can help your pond get through these brief but deadly times which are typically late winter/early spring, and late summer/fall. As aeration disperses the water, oxygen levels can reach all levels of water in the pond/lake which is not otherwise possible. This is especially true of smaller and shallower lakes and ponds that have an abundance of weeds or algae which would monopolize the low levels of oxygen available. During the summer when water is at 20 degrees, DO levels (dissolved oxygen), should be a minimum of 5 ppm. During times of the year when temperature levels are low, fish do best with dissolved oxygen (DO) levels at 4 parts oxygen per million parts water. Both levels are achievable and manageable with through aeration, ensuring fish have optimal levels of oxygen to thrive.
- When a lake or pond bottom has no oxygen fish and the food it eats cannot occupy the bottom of the pond thus reducing lake productivity. One common misconception is trout cannot live at the bottom of a pond if you aerate. Yes, rainbow trout can live throughout depths of pond if water is aerated (It is a myth that trout cannot live in ponds that are aerated down to the bottom). If you are trying to raise brook trout or char they require colder water and you will have to take measures such as aerating at night or increasing water depth water to keep water cooler.
- Heavy metals want to settle out in a solid form when oxygen is present. If no oxygen is present at the lake bottom metals stay in their ionic form and plague drinking water reservoir technicians with having to remove them with chemicals which is expensive. We use the low value of metals such as iron or manganese in water as a measure of success of our aeration system along with DO levels throughout the water column.
- Running an aeration system only at night means water circulation works to maintain the same temperature and oxygen levels that the water has during the day when exposed to sunlight. Additionally, running the system only at night can lengthen compressor life as it does not have to deal with the additional strain of running during the heat of the day.
- In short, aeration increases the rate of nutrient break down, which reduces the availability of algae food. Some nutrients (ex. organic carbon) that enter your pond can be broken down by bacteria up to 10 times faster in the presence of oxygen on the bottom.
Without oxygen at the bottom of your pond much of the decayed plant material will remain as a thick layer of black mud that slowly releases nutrients and deadly gases into the water. Anaerobic bacteria then take over and slows the rate at which wastes are removed. These bacteria also release toxins such as hydrogen sulphide gas which creates smelly water. When the sediment layer is anaerobic phosphates stay in an ionic form and are usable for plants which enables algae growth.
However, when oxygenated water flows over the sediment, organic carbon is removed by aerobic bacteria, metals and minerals are exposed and phosphates get locked up. Phosphates are the main limiting nutrient to algae and especially blue green algae (cyanobacteria) as shown by Dr Schindler through a decade of algae studies.
When a lake becomes highly eutrophic (water rich in nutrients) the delicate balance of phytoplankton, zooplankton, plants and fish is changed. Dirty water from soil erosion or fertilizer use around watercourses and lakes speeds up the process of eutrophication. When this occurs, an excess of organisms that consume all of the oxygen is consumed faster than it is replenished at the bottom of these lakes/ponds during winter and summer. Excess nutrients such as phosphate, iron and others are released from the sediment when oxygen is absent at the lake bottom (internal nutrient loading).
