Written by Industry Expert Marcus Harris, Fisheries Biologist
Picture this: you walk out to your pond on a nice sunny morning and the first thing you notice is that distinctive mucky pond smell. Rotten eggs and decomposing organics fill your nose. Maybe you see mats of pond algae on the surface or your prized fish gulping for air at the surface. Hopefully you’ve caught the problem before they are all floating on the surface. The culprit is most likely a lack of dissolved oxygen (DO) in your pond. Proper aeration can help eliminate all these problems in one quick and painless installation of a surface aerating pond fountain or a bottom aerating compressor.
First off, let’s address that smell that smacked you in the face. This is caused by anaerobic bacteria working without oxygen to break down organics built up on the bottom of the pond. These bacteria produce waste gas which bubbles up from the bottom making its way to your nose. A properly sized pond aeration system works to solve this problem by providing oxygen to the bottom thus shifting the bacteria from anaerobic to aerobic types. These aerobic types decompose organic matter producing harmless and odorless carbon dioxide waste gases. The aerobic bacteria also work much faster than their anaerobic counterparts and can pull nutrients like phosphorous from the water and make it unavailable for algae to use and take over a pond.
Aeration also provides oxygen for your fish to breathe. If there’s not an adequate supply of DO, at or below 5 parts per million, the fish become stressed and if the DO reaches 3 ppm they will suffocate. The biggest misconception about pond aeration systems is that the air coming from the compressor is providing the oxygenation. Very little oxygen is actually transferred through the bubbles; the oxygenation comes from the movement of water from the bottom up to the surface where the atmosphere provides the oxygen.
DO levels are also influenced by water temperature. There is an inverse relationship between the two, as temperature increases, DO decreases. In the middle of the summer water temperature can vary greatly from the top of your pond to the bottom. If the pond is deep enough, a temperature barrier called a thermocline can form. This barrier makes it near impossible for fish to survive in deeper parts of a pond and as the summer progresses this barrier can inch closer and closer to the surface limiting the space fish have to live. An aeration system works to evenly mix water temperature from the top to the bottom of a pond and eliminate the thermocline.
Your pond fish will be happier with the cooler water temps in the summer and aeration can also help your fish survive the winter too. In colder climates where ice covers a pond for 3 or 4 months at a time, DO levels reach an all time low. The ice acts like a cap preventing oxygen transfer between the water/atmosphere interface. As the winter progresses, DO levels continue to drop and a fish kill can result. Aeration works to move warmer water from the bottom of the pond to the top and can keep an area of the surface free of ice. This allows oxygenation of the pond. However, the open water can weaken surrounding ice so precautions should be taken to prevent children or pets from walking out on the ice.
Aeration should be an essential part of any pond management plan. It is arguably one of the best ways to achieve a healthy pond ecosystem. It provides oxygen to the bottom of a pond and allows aerobic bacteria to breakdown organic sediments and pull nutrients from the water. Aeration allows faster oxygenation of a ponds water volume to keep fish happy, and regulates the temperature keeping summertime water temps cooler.
Marcus Harris is a Fisheries Biologist with SOLitude Lake Management. Since 1998, SOLitude Lake Management has been committed to providing full service lake and pond management services that improve water quality, preserve natural resources, and reduce our environmental footprint. Services are available throughout the Eastern United States. Fisheries management consulting and aquatic products are available nationwide. Learn more about SOLitude Lake Management and purchase products at www.solitudelakemanagement.com.
Contact the experts at 888-480-LAKE (5253) for all of your lake, pond and fisheries management needs.