Cracking the algae code: Navigating the pool’s microscopic invaders

by arslan_ahmed | December 22, 2023 4:00 pm

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By Alicia Stephens

The primary concern for any pool owner is the unpleasant sight of a green pool. Nobody wishes to gaze into their backyard and see murky, green water or a pool overrun by algae when it should be crystal clear. There are many different types of algae in the world, and several of them can flourish in the pool environment. As such, a critical aspect of pool water maintenance is averting algae growth, making it essential for both pool owners and service professionals to include a weekly preventive algaecide as part of their routine. Taking a more in-depth view, one can explore strategies to prevent the proliferation of algae and identify the necessary steps to address an algae outbreak.

Understanding algae in pools

The first question that always comes up concerns the origin of algae. In certain scenarios, a pool can undergo a rapid transition from crystal clear to swampy green overnight, making it challenging to determine its source. Algae is consistently introduced to the pool from a variety of sources. Algae spores from various species can be traced back to natural water bodies, plants, soil, and trees. Further, rain, wind, swimmers, and animals—specifically birds—are among the various contributors responsible for introducing algae to pools. In fact, a single bird can introduce more than 100 different types of algae to the pool environment. The short answer is algae find their way into pools from virtually everywhere.

In the absence of adequate algae prevention measures, once algae spores are introduced into the pool, they will immediately start to grow and reproduce. Left unchecked, a single algae cell can ultimately multiply into more than one million algae cells, leading to a significant algae bloom in the pool. A fundamental strategy for maintaining clean and clear pools is to proactively hinder the growth and reproduction of algae from occurring. Addressing an outbreak is substantially more challenging than preventing one in the first place.

In the pool industry, algae are typically categorized into three main types: green, yellow (or mustard), and black algae, each characterized by distinct attributes. Green algae is often the easiest to get but also the simplest to eliminate. While pools can turn green quickly, they can be cleaned up swiftly in most instances. In many cases, employing an Environmental Protection Agency (EPA)-registered chlorine-based shock treatment, along with effective circulation and filtration, can take care of the issue. Yellow algae, also known as mustard algae, has a yellowish appearance and is commonly found on the bottom of the pool. When disturbed (e.g. by brushing), it tends to disperse (fluff up) but typically settles back in the same area, making vacuuming it up a difficult task. Black algae, although it is not algae but cyanobacteria, manifests as a distinct growth on the pool surface. It adheres firmly, rooting itself into the plaster and becomes quite difficult to brush up and remove. The most effective approach to eliminate black algae usually involves vigorous brushing and direct application of chlorine or algaecide. It is essential to perform a spot test in the targeted area before employing direct application treatments.

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Many experts in pool maintenance have devised specific strategies for addressing each type of algae, essentially creating tried-and-true recipes for effective removal. Recently, however, a team of scientists and chemists from one chemical manufacturer conducted targeted research to explore more effective methods of preventing and eliminating the algae commonly found in pools.

This research entailed a comprehensive review of publications on algae research, coupled with the collection of algae samples from various pool environments, as well as test pools in the manufacturer’s research facilities. After gathering these naturally occurring algae samples, they were identified and categorized. Subsequently, a wide variety of experiments were conducted to determine the most effective means of controlling and eliminating each unique sample.

As discussed above, the pool industry typically classifies algae into three broad groups (despite there being 13 major categories of algae). These groupings are established based on a range of characteristics, including the types of chloroplasts present in the algae cells, the sources of nourishment they rely on, the composition of the outer membrane of the algae cell, their capacity for mobility via flagella, and numerous other features. These distinctive characteristics play a pivotal role in determining the best practices for algae prevention and treatment, surpassing the traditional reliance on the colour or location of the algae as the primary classification criteria for pools.

The battle against green algae

The most common type of green algae in pools is called Chlorella sorokiniana. Chlorella sorokiniana is a vibrant green colour and makes up the majority of green algae discovered in the pool samples examined in the study. It is controllable using chlorine and most algaecides commonly integrated into pool care programs (Figure 1).

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Interestingly, within the “green” algae samples, a distinct form of algae, known as Scendesmus acutus, was also detected. This type of algae represents an entirely different species of green algae compared to what is typically acknowledged in the industry. Visually, when inspecting a pool, the only apparent distinction is the algae is green, with no observable disparities between the two species unless placed under a microscope. Under the microscope, Chlorella sorokiniana appears round and singular, while Scendesmus acutus, takes on an oval shape and forms long chains of algae cells in groups.

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As the research progressed into the effective eradication of green algae, it became evident that while Chlorella is easily killed by chlorine, quaternary (quat) or polyquat-based algaecides, and copper-based algaecides, Scendesmus acutus exhibited lower susceptibility to low copper residuals. Has one ever used a copper-based algaecide and expected it to clear the pool quickly, only to discover that it proves ineffective in combating the algae growth? In such scenarios, even repeated applications may not yield better results. The green algae in the pool could, in these cases, be Scendesmus acutus, opposed to the more commonly encountered Chlorella. Unfortunately, differentiating between the two at the poolside is not feasible.

Unveiling the mustard algae secrets

Further, this research delved into an extensive examination of mustard algae. The most common type found in a pool is known as Eustigmatos vischeri. This algae displays a yellow hue and exhibits the common characteristics associated with mustard algae, such as settling at the pool’s bottom, able to be brushed, and presenting control challenges. The image of Eustigmatos vischeri provides insight into why it can be difficult to treat in pool water. As depicted, this algae species is round and appears to be covered by a hard outer shell. This shell can make some species of Eustigmatos more resistant to chlorine, necessitating elevated chlorine levels for effective control. However, copper-based algaecides are highly effective against mustard algae because they are ingested into the algae cell, bypassing the need to breach the outer cell wall.

In the process of classifying mustard algae, real world pool samples yielded a different species that looked like mustard algae in the pool but was an entirely distinct organism. On the surface, it appeared to be Eustigmatos vischeri, however, it was actually Nitzschia communis (Figure 2).

Nitzschia communis is a diatom that presents as mustard algae but is a completely different organism. It has flagella and is capable of independent movement within the water. It primarily feeds on silica to enhance the reserves needed for its survival. In a pool environment, a continuous supply of silica is offered to these diatoms through a sand filter or other dirt and debris from the pool’s surrounding environment, enabling them to grow and reproduce. In many cases, recurring mustard algae outbreaks in pools can be attributed to the failure to chemically clean the filter following an algae treatment.

If Nitzschia communis is growing in a pool, not cleaning the filter will allow it to persist and reproduce even after treatment. Consequently, the entire pool is susceptible to reinfestation, perpetuating the cycle. Thoroughly cleaning the filter with chemicals after an algae outbreak is a critical component of the treatment process. In addition, the presence of dirt (which contains silica) in poorly circulated areas at the bottom of the pool can lead to an environment where conducive to the growth and reproduction of Nitzschia communis.

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Dealing with black algae (cyanobacteria)

The final classification of pool algae is “black algae.” As mentioned, black algae is not a genuine algae but rather cyanobacteria. It has a filamentous nature, anchoring themselves into the pool surface to establish growth. These filaments create challenges in releasing “black algae,” or cyanobacteria, from the pool surface for treatment. In addition to filamentous roots, cyanobacteria have a hard outer shell covering their layers of growth, making brushing an important part of the treatment process. Common consensus says cyanobacteria are more likely to thrive in areas of the pool surface that are rough or damaged, allowing them to take root. Based on the research conducted by the team, it revealed that cyanobacteria was most likely to grow in areas of the pool with poor circulation. Typically, cyanobacteria are often found in pool corners and on steps, areas characterized by poor circulation and conducive conditions for cyanobacteria to root and grow. This is one of the many reasons why routine pool brushing is an important part of weekly maintenance, regardless of whether any visible issues are present.

This research findings confirmed the presence of various naturally occurring algae types in pools. It is impossible to identify the exact type of algae growing in the pool just by looking at its colour in the water. The study demonstrated a mixture of different algae types in most of the collected samples, making it difficult for service professionals working poolside to discern the appropriate treatment required to effectively combat and prevent algae outbreaks.

While there is no silver bullet to keep in one’s toolbox to rely on exclusively, this research should encourage service professionals to consider a variety of approaches to treat different types of algae they might encounter in the field. Chlorine is a great algaecide and is effective against many types of algae found in pools. Typically, maintaining the standard sanitizer residuals is sufficient for preventing algae outbreaks. However, allowing this level to drop below the recommended range, even for a short period, can allow fast-growing algae to start spreading.

Once algae growth has started, it may require higher sanitizer levels to control them. Therefore, it is much more practical and cost-effective in the long term to consistently maintain the standard sanitizer level in the water. Chlorine’s primary job is to kill bacteria in the water, and the pool’s sanitizer is the sole chemical capable of doing so. While using chlorine to combat algae can be effective in most cases, it does use up a substantial amount of chlorine in the process, leaving less behind to kill bacteria. In contrast, other algaecides, such as quats, polyquats, or copper-based algaecides are solely dedicated to eradicating algae, ensuring chlorine remains available for bacteria control.

The research focused on finding an effective way to kill algae, independent of the sanitizer and without adverse effects such as foaming or staining. In general, the characteristics of algaecides indicate chlorine can be effective in many cases, but quats and polyquats are easier to help manage water chemistry. These positively charged molecules are drawn to the negatively charged cell walls of algae, acting like a magnet to bring the algaecide and algae cell together. Then, the quat or polyquat will tear open the algae cell wall, causing the algae cell to die.

Copper algaecides work differently by being ingested into the algae cell, effectively shutting down the internal processes and enzymatic reactions that keep the cell alive. Copper algaecides are highly effective against many algae species and are often among the fastest acting treatment options. Since most algae blooms in pool water are a mixed bag of algae species, it can be difficult to determine which algaecide will be the most effective. Consequently, some pools may not respond to traditional algae treatments or may require additional product doses to clear the water.

Although dealing with algae in pools can be frustrating, issues are not common if the water is properly maintained, and appropriate pool care procedures are followed. Maintaining a consistent sanitizer residual, weekly shocking, and regular application of an algae preventative treatment are key to preventing algae outbreaks. If problems do occur, using a strong algaecide along with chlorine-based shock treatment can help clear the water quickly and restore its clarity, making it suitable for swimming. Ultimately, while algae can be a problem, they can be effectively prevented through diligent pool care maintenance, ensuring a beautiful pool that is always ready for swimming.

 Author

Alicia Stephens is the director of training and education for BioLab Inc. In her 23 years with the company, she has focused primarily on education, training, and development, as well as technical support and new product research and integration. Currently, Stephens supports all education and training initiatives for the BioLab Pro Dealer division.

Source URL: https://www.poolspamarketing.com/trade/features/cracking-the-algae-code-navigating-the-pools-microscopic-invaders/

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