Controlling Lake and Pond Algae

Lakes and ponds are the place we head to for enjoyment to swim, fish or relax. Unfortunately it is also the perfect environment for algae to grow. Where there is sun, water and nutrients pants will grow. And since algae is a very basic and simple form of life, it will be one of the first to establish itself and the quickest to rebound from steps taken to eradicate it such as herbicides.

A pond is a closed system functioning much like an organism with all the life within interacting to create a balance. Algae, rooted plants, zooplankton, fish, birds and so on all have their part and keep the other parts in check and under control. Too often this balance tips and the system spirals out of control. Algae, being the opportunist that it is, is usually the first to take charge. Thick mats of slime or pea green soup-like water are the result.

This is usually a sign of high nutrients and poor water conditions. In the summer and winter months a pond often becomes stagnant and a thermocline forms. As this forms, the water column is cut into two regions. An area of livable water near the surface and a layer of toxic oxygen deficient water closer to the bottom. This upper livable area is susceptible to wild swings in quality as the algae growth spikes and drops, first giving oxygen then sucking it back out as it goes through respiration near dawn or decomposes after a die off. In the spring and fall these two regions will suddenly and violently mix, called a turnover event. It is these turnover events that can trigger a fish kill as the toxins are released to the entire water column stressing all fish contained within the lake or pond.

One very effective technique to prevent this situation is to aerate the water column of the lake or pond. By aeration we mean using laminar flow methodology (bubblers) to move the water from surface to the bottom. Fountains do work in certain situations, such as shallow water areas. But only laminar flow has the ability to completely mix even the deepest of areas to get oxygen down to the sediment-water interface. The thermocline is prevented from ever setting up and the entire water column is improved.

The tiny bubbles pull the water with them as the travel to the surface. The water pulled up from the deep are exposed to the atmosphere and two things happen at the surface. Toxins from the natural bacterial digesting process are released harmlessly to the air while oxygen is absorbed into the water. This oxygen rich water is then pushed back down to the bottom to release the oxygen to the bacteria and move the toxins back to the surface. It functions as a toxin/oxygen conveyor belt that keeps the system in balance.

Once oxygen is in all areas natural bacteria are able to consume nutrients available in that water. Aerobic bacteria, those with oxygen available, can digest nutrients SEVEN times faster than bacteria forced to go through anaerobic, without oxygen, conditions. This reduces the available nutrients for algae to use to grow. It is an indirect method to outcompete the algae for the food they need to survive.