Five proactive strategies for minimizing harmful algae growth
A little fact… Cyanobacteria can grow and spread in nearly any body of water but are especially adept at multiplying in slow-moving and calmer waters, expanding significantly as a result of static water environments.
So what about freshwater? In freshwater lakes, ponds, and reservoirs, harmful algae blooms (HABs) are most often the result of cyanobacteria, most commonly known as blue-green algae. Most of these types of algae are naturally heavier than water but have built in buoyancy that allows them to come to the surface for sunlight. This buoyancy regulation keeps them at the same density as water, so small changes allow them to sink to the bottom for nutrients at night and also come to the surface early in the day for sunlight. As they cover the surface, they shade out the sunlight for other types of algae and plants below causing them to die. The dying biomass is consumed by bacteria causing a host of other issues such as depleting oxygen levels (bad for fish) as well as producing foul smells. As they die, they release nutrients like phosphate that in turn feed the cyanobacteria bloom making it grow even faster. Cyanobacteria are much older as a species and share many of the same attributes as algae such as the ability to photosynthesize. Thanks to their waste product, oxygen, we can breathe.
Cyanobacteria are much older as a species and share many of the same attributes as algae such as the ability to photosynthesize
The threat of cyanobacteria has been increasing for years and with the rise in temperatures is becoming more of a problem. They are destructive and harm aquatic ecosystems, people, animals, drinking water supplies, the economy, recreational activities and everything we hold dear. In fact, it’s a worsening worldwide problem that requires immediate attention.
Before getting into the solutions, it is necessary to describe the primary cause of cyanoHABs or harmful blooms of cyanobacteria. These dangerous algae can bloom with extremely small amounts of phosphate pollution that gets into a water body. Phosphates typically come from farm fertilizer runoff, over fertilization of lawns, phosphate-based cleaning soaps and surfactants. Overuse of algaecides (particularly the long-term use of copper sulphate) can eliminate useful beneficial bacteria in the sediment which can result in less phosphate consumed so more phosphate gets released. This is because the remaining bacteria unaffected by the copper sulphate are mostly anaerobic and they eventually cause the algae problem to spiral out of control by continuing to recycle phosphates back into the water column. This then fuels cyanobacteria, creating complex hydrocarbons that are poisonous to many organisms, including animals and humans.
Strategies and solutions to shut down harmful algae growth
Over the past decade, technologies have evolved to better manage cyanobacteria and other algae. While it can be a challenge to rank which products and approaches may be most relevant for a particular situation, the five proactive approaches below provide an overview of the solutions currently available to significantly lower the risk of a HAB and effectively manage the problem.
Ultrasound – Today’s ultrasonic algae control solutions are a technological leap beyond the first systems that came to market more than two decades ago. The latest systems transmit more than 2,000 frequencies to leave no stone unturned to target the most harmful cyanobacteria, so the effect is an order of magnitude greater compared to previous generation products. This makes the right ultrasonic algae mitigation platform an excellent preventative and active remedy to HABs. The most modern devices use critical structural resonance to achieve disabling both algae and cyanobacteria and avoid cavitation that can cause burns if touched by human skin.
Cyanobacteria are destructive, harming aquatic ecosystems, people, animals, drinking water supplies, the economy, recreational activities
It has been estimated that approximately 95% of the 70,000 species and two million sub-species of algae can be efficiently mitigated with ultrasound. This approach has been proven to be highly effective in thousands of lakes, ponds, and other water repositories at addressing a broad range of algae and cyanobacteria. These systems are a chemical-free solution, are safe to use, and do not upset the ecological balance of the environment.
Nutrient Mitigation – Beneficial bacteria are useful for removing excess phosphate, the primary nutrient that triggers algae blooms, by consuming the phosphate and converting it to a non-soluble form (polyphosphate) that remains in the bacterial cells. This removes it from the water column and the muck, preventing it from being continually recycled back into the water.
Aeration– Lakes, ponds, reservoirs, and other water body aeration products deliver water circulation and increase the amount of dissolved oxygen throughout the area, resulting in the reduction of nutrient/sunlight-driven cyanobacteria growth. One of the more common and visible forms of aerators are fountains and surface aerators. In deeper ponds (i.e., greater than 6 feet), bubbler-type diffusion aeration is most beneficial. The additional oxygen these provide to the water makes algae growth much more difficult by greater circulating the water from top to bottom. Aeration should not be viewed as the only solution in algae remediation especially when nutrients such as phosphorous are abundant.
Algaecides- Algaecides are chemical compounds that when applied to an area showing early signs of cyanobacteria or full infestations, kill the algae and either prevent or destroy a harmful algae bloom. There are several examples of these, including:
- Copper-based algaecides (copper sulphate, copper II alkanolamine, copper citrate, etc.)
- Potassium permanganate (can reduce water dissolved oxygen and works as an oxidizer)
- Chlorine (works to disinfect bacteria and algae – not for ponds with fish or other wildlife)
- Hydrated lime (cannot be used in ponds with fish due high pH change on addition)
- Hydrogen peroxide (sodium carbonate peroxyhydrate – dissolves to release hydrogen peroxide)
Hydrologic Manipulations – Capably applied, the manipulation of inflow/outflow of water in the system to agitate the water column and disrupt stratification helps to control the growth of cyanobacteria. While the infrastructure necessary to leverage this process can be expensive, once in place it can be an effective component of an algae prevention process. This option requires a sufficient volume of water and the ability to control the flow. While this is a recognized industry solution, there can be undesirable impacts to some life forms in many situations so hydrologic manipulation applications must be completed with care.
The application of these preventative algae management approaches is critical to preserving the viability of the water source and preventing harm to life in and around the water source. Many water quality professionals use a combination of these solutions, like ultrasonic systems and nutrient mitigation (good algae) solutions to prevent or expedite the remediation of algae. As municipalities and governments seek out safe, yet effective algae control methods to prevent and alleviate cyanobacteria algae growth, the above solutions are available today and have proven effective across a wide range of environments.
By leveraging these technologies and processes for preventative algae control, there likely isn’t an algae problem that water management professionals haven’t experienced over the years and haven’t been successful in ultimately treating. After the deployment of one or more of the above systems – sometimes used in combination - observers will see an instant defence against cyanobacteria to keep its growth at bay. For those with an active area of cyanobacteria growth, there will be a rapid decline, with a significant reduction – typically within 30 days.