Lake and Pond Aeration in Tennessee: the Basics
If you have owned all or part of a lake or pond in Tennessee for more than five minutes, you have probably looked into aerating said water body. And with good reason: aeration can make the difference between a healthy lake or pond, and a massive fish kill. But not all aeration is created equal; you need to know the differences (unless you enjoy seeing your prized trophy fish floating dead all across the lake).
As with any hotly-contested industry, there are companies operating in the lake and pond management space in Tennessee that have decades of experience in the field, and then there are companies that just entered the fray a month or a year ago because they thought they could score a quick profit. The first rule of thumb in choosing a company to install aeration for your lake is this: get someone who actually has been doing it a while, so they at least have a chance of being competent. If you hire that fledgling company whose sole employee for this state graduated college nine months ago and is eager to have your pond as his very first field experience, you may end up with results that you don’t cherish.
Even among companies that have been doing this a while, there are those that are known for developing high-level fisheries...and there are those that are known for being big companies with hundreds of employees, but have never been called by any biologist anywhere experts in fish management. Companies in the latter category tend to sell you whatever they think you want, regardless of whether it will actually do what you want it to do. When it comes to aeration, this translates to one thing: fountains.
We get multiple new clients every year that mention in our initial phone conversation that they already have their lake or pond aerated, and then they mention that the aeration is a fountain. So then I have to explain to them that a fountain won’t protect them from a fish kill.
Most ponds that are not aerated with a bottom-diffuser aeration system will stratify in the warm months into two layers; the point where this stratification occurs is called the thermocline, the upper, oxygen-rich layer of water above the thermocline is called the epilimnion, and the lower, anoxic layer below the thermocline is called the hypolimnion. The hypolimnion will typically not have enough dissolved oxygen for fish or anything else to live. If you’ve ever heard someone talk about losing all of their fish to a turnover fish kill, turnover happens when the two layers mix too quickly, trapping fish in
bad water. A bottom-diffuser aeration system, while it will not prevent all types of fish kill, will prevent a turnover kill because it mixes the entire water column constantly from the bottom to the top. As the oxygen-poor water is brought to the surface, it interfaces with the atmosphere and takes on oxygen. Lakes or ponds aerated with a bottom-diffuser system tend to have consistent oxygen levels from the surface to the bottom.
A fountain, conversely, does add oxygen to the water, but it only adds it to the epilimnion, the layer that already has plenty of oxygen in the warm months from phytoplankton. A phytoplankton bloom blocks sunlight from penetrating to the pond bottom; this means there won’t be any photosynthesis happening at the pond bottom, which means phytoplankton can’t live there; so no oxygen is being emitted into the water by phytoplankton in the hypolimnion, which is why it becomes anoxic in a pond that isn’t aerated with a bottom-diffuser system. But if the pond has a bottom-diffuser system, that water on the bottom is being constantly brought to the surface where the oxygen is, and it stays oxygenated. We have done electrofishing surveys on many lakes and ponds that had only fountains for aeration, and it’s common to find thermoclines in such waters, which means they’re at risk for fish kills.
Another disadvantage of fountains is that they require a power cord going out into the pond or lake, whereas a bottom-diffuser system does not. With a bottom-diffuser system, the only components that go in the lake or pond are airline tubing and the diffuser stations, and these components are the ones that always have the longest warranties, because they’re very simple components and not prone to problems. Fountains are only prone to problems when installed into lakes or ponds. As in, it’s rare for us to acquire a new client who has a fountain and not have that person ask if we can fix their broken fountain.
Another type of lake and pond aeration is what’s called agitator aerators. These are mainly used in commercial fish farming operations; like fountains, they require a power cord going out into the water; like fountains, they are highly prone to mechanical problems and constant breakdowns. Unless you’re managing your lake or pond more like an industrial hatchery than a recreational fishery, you don’t need an agitator aerator. You’ll spend more time trying to keep it running than you will fishing the lake.
