Q: What is the thermocline?
Walt – Cedar City, UT
A: Have you ever swum in a pond without a bottom aerator and felt colder water near your toes and warmer water on top?
You’ve experienced the thermocline.
Simply put, the thermocline is a layer of water between the warmer, surface zone and the colder, deep-water zone.
In ponds and lakes in the summertime, a natural phenomenon called stratification occurs when warm, less-dense, oxygen-rich water sits on top of colder, denser, oxygen depleted water. The thermocline separates the warm layer—the epilimnion —and the cold layer—the hypolimnion. In this stable system very little mixing of the layers occurs, particularly in calm weather.
Fish and other underwater critters (including beneficial bacteria) have trouble with this stratification. As summer marches on, your finned pals have less and less oxygen available below the thermocline, so they have to come closer to the surface to get their needed O2 supply. That means less room for them to swim. It also means your beneficial bacteria below the thermocline become oxygen-starved, which could result in algae growth and odor.
Thank goodness for aeration.
Bottom diffuser aeration, like Airmax® Aeration systems, prevents your pond or lake from stratifying by churning and mixing the temperature layers. The tiny bubbles created by the diffuser force the cooler oxygen-starved water to the pond’s surface where it becomes pumped up with O2. The warmer, oxygen-rich water then drops down, fueling the beneficial bacteria.
The result is an eliminated thermocline and higher oxygen levels throughout the water column.
It’s critical, however, that your system be sized correctly for your pond so the aeration is uniform throughout. If you currently have an aeration system running and you’re not sure if it’s doing its job, take your pond’s temperature. Using a thermometer and string, measure the temperature of the water every 24 inches down in various locations in your lake. If you find that you have more than a few degrees difference in your vertical readings, you’re probably under-aerating your pond.
But once you get your aeration system dialed in, your fish will once again have full access to the entire body of water, and your beneficial bacteria will have the opportunity to grow and thrive.
Call us if you need help mapping the aeration system in your lake. We’re happy to help!
Pond Talk: Have you experience stratification in your pond or lake?