One of the most common questions asked is, “Where to place diffusers when considering pond aeration?”
Some “experts” claim that aeration is best when diffusers are placed in the shallower parts of a pond, others the deeper parts, and some say it is best when placed somewhere in between. The truth is that diffusers typically operate best in the deepest part of the pond. For example, if your pond is 12 feet deep at its deepest point, then you should try to set at least one diffuser in that 12-foot area.
The most important reason to place your diffuser in the deepest part of your pond is to get the water circulating. Water in the deepest part of the pond should rise to the surface, come in contact with both sunlight and wind, and get an injection of much needed oxygen. This water then circulates back down to the bottom of the pond where it is full of life-giving oxygen for both fish and aerobic bacteria. Without oxygenating your deeper water, you could have 2-4 feet of unhealthy stagnate water resting at the bottom of your pond. This water stays cold and remains anaerobic (without oxygen), doing little to aid in the decomposition of organic matter, or “muck,” on the floor of the pond. Most fish find this area unusable for any length of time due to the lack of oxygen.
Well-aerated ponds and lakes support a larger number of fish by offering them a greater area of living space. As water circulates, it also provides a more uniform temperature and oxygen concentration, thus eliminating thermal stratification. Pond aeration can be achieved through the use of windmill aerators, solar aerators, or electric aerators. All three options are effective and supply oxygen necessary for the digestion of algae, ammonia, and nitrites. Pond and lake aeration is proven to increase the number of aerobic bacteria that assist in the decomposition of fish waste, leaves, and other organic matter. This not only helps reduce the amount of “muck” or “sludge” on the bottom, but also helps eliminate pond odors.
There is one possible exception to this rule. Species of fish that dwell in cold water, such as trout, walleye, northern pike, and muskie, need colder water to survive, so placing your diffusers 2-3 feet from the deeper holes is preferred. You do not need to “suspend” your diffusers; instead, set them in an area of the pond that is slightly shallower than the deepest hole.
In summary, deep-bottom diffuser aeration of a pond or lake is probably the single best investment you can make regarding the sustenance of your pond. Once you have your diffusers, placing them in the correct location will ensure that water is circulated from the deeper parts of the pond to the surface, providing valuable oxygen to your pond life in the process.