Winning the War on Algae

Winning the War on Algae

water quality analysisA perfect golf course is so much more than just lush, healthy turfgrass. It’s the balance of grass, sand, water, and the interaction with the surroundings that give you that “this is gonna be a great game” feeling. Rolling up next to a pond covered in green slime infringes upon that feeling. But! You can’t just nuke all the plant life in your waters because they contribute to the ecosystem’s health. Like so many things in this industry, it’s about balance. Here we talk about algae and its role in your ponds. 

Ponds are an integral part of the golf course landscape and also serve as a source of recreation to many homeowners throughout the world. However, ponds contribute much more than just aesthetics. Ponds are delicately balanced ecosystems containing essential nutrients, algae, zooplankton, fish, frogs, turtles, plant life, and water fowl, each of which is integral in maintaining proper pond health. Maintaining pond water quality can be expensive and frustrating. It can cost hundreds of dollars to clean up ponds, often using chemicals only to have the problem reoccur in a few weeks. A long-term solution requires an understanding of pond biology. Unfortunately, most ponds are susceptible to unhealthy/harmful algae blooms. Why is this?

The answer isn’t simple, but does involve excess nutrients and stagnant water. How does one gauge the health of a pond? The easiest way to gauge the health of a pond is by looking at it. A healthy pond is clear, with just a slight tint of green (beneficial algae). Anything else would likely mean that there are some imbalances present.

“A healthy pond is clear, with just a slight tint of green (beneficial algae).”

What is needed for a healthy pond?

A pond needs a predator-prey relationship in order to maintain its health. Single-celled algae (green algae) and diatoms are the primary producers that capture energy from the sun and convert nutrients (carbon, nitrogen, phosphorus, etc…) into usable energy for other living organisms. Green algae are small enough to be eaten by zooplankton, which in turn are the right size to be eaten by fish. This ongoing predator-prey relationship keeps the level of algae, zooplankton, fish, dissolved oxygen, and pH all within a normal, healthy range.

In addition to visual inspection, there are other, more technical ways to gauge the health of a pond. A pond must have sufficient levels of dissolved oxygen to properly support the food chain. Levels often range from 0 ppm (complete lack of oxygen) to around 9 ppm (the saturation point in water during characteristic summer temperatures). The normal dissolved oxygen content of a healthy pond ranges from 5 to 9 ppm, day or night, based on normal photosynthesis and respiration of a typical algal colony controlled by zooplankton.

If a harmful algae bloom (blue-green algae) were to occur, where the algae are inedible and unable to be controlled by zooplankton, the dissolved oxygen levels may range as high as 12 to 25 ppm in the day and drop to 0 to 4 ppm at night (due to algal respiration at night). Additionally, if there are excessive levels of nutrients present, any blue-green algae bloom will become much larger. Eventually the bloom will become light limited, and the blue-green algae will all perish. When this happens, the bacteria that decompose the dead algae cells do so all at once, using all of the oxygen which can lead to significant fish kills.

“In general, a pond will stay healthy if the upper warm water is circulated at several points with the cool water from below.”

In general, a pond will stay healthy if the upper warm water is circulated at several points with the cool water from below. This circulation assists small-celled algae in the pond by allowing them to be exposed to more nutrients and by re-suspending them in the water column, which is important because the good green algae are heavier than water and will sink out of the sunlight over time.

Blue-green algae (bad algae) on the other hand have several weapons in their arsenal to gain an advantage over the edible green algae (good algae). One such weapon is that blue-green algae can change their buoyancy. Blue-green algae thrive in waters that are nutrient rich, especially after a few days of calm winds, warm temperatures, and sunlight, because without wind or good mechanical mixing, the good green algae will settle to the bottom and die. When this happens the blue-green algae can go to the surface during the day for sunlight and then sink at night to gain access to the nutrient-rich waters at the bottom of a pond. In addition, blue-green algae have other advantages such as they contain toxins that can kill zooplankton and other organisms, they can store phosphorus for later use, and they are nitrogen fixers (so they can get their own nitrogen from the air). As a result, once blue-green algae take over it is very difficult for the good algae to displace them.

“Once blue-green algae take over it is very difficult for the good algae to displace them.”

The good green algae do have a couple advantages of their own over the blue-green algae. First, they start growing much earlier in the season, which gives them a head start competition-wise and secondly, the green algae reproduce many times faster than blue-green algae. So how can we help give the green algae more of a competitive advantage? Wind mixing alone is not enough to help the green algae out-compete blue-green algae because blue-green algae have adapted over the years to predictable wind mixing patterns. However, if the water column can be properly circulated, green algae can consume the available nutrients quite rapidly and remain viable throughout the season, making it harder for blue-green algae to gain a competitive edge.

Research has shown that near-laminar flow horizontal mixing of a pond is an effective tool to improve water quality. In shallow ponds water is drawn from the bottom and in larger ponds water is drawn from just above the thermocline from all directions and is sent out across the surface of the pond in a thin layer. The constant horizontal and vertical movement provides gentle mixing and surface renewal, thus giving green algae an advantage. The goal is not to add oxygen to the pond, but it is to help the green algae survive so that they can provide oxygen to the pond and then be a food source for zooplankton.*

Soil & Water Consulting can help with your Golf Course Water Quality Analysis

We are not a one-trick pony at Soil & Water Consulting. “Water” is even in our name! We can help assess and monitor your water quality in your ponds and in your irrigation systems to ensure you’re finding the balance you need to achieve the highest quality results. Call us today to find out how we can help.

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*Winning the War Against Algae was written by Luke Baker, Ph.D. at Brookside Laboratories