Field Sampling of Swimming Pool “Black Algae”: Continued Investigation into Cyanobacterial Biofilms
This article discusses the significance of Field Sampling of Swimming Pool “Black Algae” in maintaining pool water quality.
A colleague once joked that seeing me step into a public pool to collect algae samples would be a bit like watching meteorologist Jim Cantore arrive just before a hurricane makes landfall—you know something unusual is about to happen.
Understanding the process of Field Sampling of Swimming Pool “Black Algae” can lead to better management practices.
While humorous, the comment reflects how uncommon it is for field microbiological sampling to occur directly within operational swimming pools. Yet field sampling remains an essential step when investigating persistent microbial growth in aquatic facilities.
The Field Sampling of Swimming Pool “Black Algae” technique allows for accurate microbial assessment.
In November 2018, additional specimens of what pool professionals commonly call black algae were collected as part of an ongoing investigation into the microbiology of swimming pool biofilms.
Our research focuses on Field Sampling of Swimming Pool “Black Algae” to identify underlying issues.
Earlier Findings from Florida Sampling Sites
Data collected from Field Sampling of Swimming Pool “Black Algae” informs future studies.
Previous samples collected in Atlantic Beach, Florida during October 2018 had already revealed an important discovery.
Laboratory analysis identified Leptolyngbya species, a filamentous cyanobacterium, as the dominant organism within the biofilm biomass. This differed significantly from earlier specimens collected in Gainesville, Florida, which contained different cyanobacterial genera including:
Utilizing Field Sampling of Swimming Pool “Black Algae” enhances our understanding of microbial diversity.
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Oscillatoria
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Microcoleus
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Nostoc
These findings suggested that microbial communities within swimming pool biofilms may vary significantly across geographic locations, a phenomenon consistent with broader biofilm research.
The implications of Field Sampling of Swimming Pool “Black Algae” are significant for pool operations.
Scientists studying microbial biofilms have long recognized that environmental conditions—such as temperature, nutrient availability, and surface characteristics—can influence the composition of microbial communities. Research conducted by the Center for Biofilm Engineering at Montana State University has demonstrated that biofilm populations frequently vary across locations even when environmental systems appear superficially similar.
Our findings from Field Sampling of Swimming Pool “Black Algae” could lead to improved pool maintenance strategies.
The discovery of Leptolyngbya in the Atlantic Beach samples reinforced the idea that what pool professionals identify visually as black algae may actually represent diverse cyanobacterial biofilms rather than a single organism.
Implementing Field Sampling of Swimming Pool “Black Algae” is crucial for ongoing research.
However, unlike some cyanobacteria genera, Leptolyngbya is not widely associated with cyanotoxin production, which meant further sampling was necessary to continue investigating the potential relationship between swimming pool biofilms and toxin-producing cyanobacteria.
Returning to Gainesville for Additional Samples
Additional Field Sampling of Swimming Pool “Black Algae” is planned to gather more data.
Because the earlier Gainesville samples contained cyanobacteria genera historically associated with toxin production, it was logical to return to the same geographic area to obtain additional specimens.
A swimming pool located less than one mile from the site of the original Gainesville sampling provided an opportunity to collect additional colonies exhibiting similar dark surface growth.
The sampling location was selected because previous specimens from the region had already been examined by University of Florida phycologist Dr. Edward Phlips, whose work contributed to the early identification of cyanobacteria in swimming pool biofilms.
Our team emphasizes the importance of Field Sampling of Swimming Pool “Black Algae” for accurate results.
Challenges of Sampling in Operational Pools
Challenges faced during Field Sampling of Swimming Pool “Black Algae” can inform future methodologies.
One challenge associated with field sampling in active swimming pools is the presence of disinfectants and chemical treatments that may influence microbial detection.
Each instance of Field Sampling of Swimming Pool “Black Algae” contributes to a larger body of knowledge.
At the time of collection, the free chlorine concentration in the pool water measured approximately 10 ppm free available chlorine (FAC), with cyanuric acid levels exceeding 100 ppm. Chlorine is a strong oxidizing agent, and studies published in water treatment literature demonstrate that chlorine can degrade many cyanotoxins under appropriate conditions.
This raised an important analytical concern.
If cyanotoxins were present within the biomass, the disinfectant concentration might oxidize the toxins before they could be detected in surrounding water samples.
Because the pool belonged to a third party, altering the chemistry of the water prior to sampling was not an option. The specimens therefore had to be collected under the existing chemical conditions.
Field research in operational pools frequently involves similar limitations, requiring investigators to work within the parameters of existing pool water chemistry.
Through Field Sampling of Swimming Pool “Black Algae”, we observe varying results across pools.
Sample Handling and Laboratory Submission
The collected biomass samples were refrigerated immediately following collection to preserve microbial structure prior to analysis.
Instead of shipping the samples, the specimens were personally transported to GreenWater Laboratories in Palatka, Florida, a laboratory known for its expertise in cyanobacteria identification and toxin analysis.
Upon arrival, a chain-of-custody protocol was completed to document the sample transfer. The initial analysis requested was a Potentially Toxigenic (PTOX) Cyanobacteria Screen, which identifies cyanobacteria genera that have historically been associated with toxin production.
Only after confirming the presence and identification of cyanobacteria could appropriate toxin analyses be selected.
Cyanobacteria Screen Results
The Field Sampling of Swimming Pool “Black Algae” results are crucial for understanding biofilm behavior.
On November 7, 2018, phycologist Andrew Chapman, M.S. of GreenWater Laboratories reported the results of the PTOX cyanobacteria screen.
The laboratory again identified multiple cyanobacterial genera within the biofilm biomass, including:
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Leptolyngbya
Future studies will continue to focus on Field Sampling of Swimming Pool “Black Algae” for improved protocols.
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Oscillatoria
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Synechococcus
The presence of multiple cyanobacteria genera further supported earlier observations that swimming pool black algae represents a complex microbial biofilm community rather than a single species.
Among the organisms detected, Oscillatoria species are known in scientific literature to include strains capable of producing microcystins, a class of hepatotoxins produced by certain cyanobacteria.
However, it is important to emphasize an essential point recognized in microbiological research:
Insights gained from Field Sampling of Swimming Pool “Black Algae” may influence public health policies.
The presence of a cyanobacteria genus associated with toxin production does not necessarily mean that toxin-producing strains are present.
Even within toxin-producing genera, many strains do not produce toxins at all.
Environmental conditions such as nutrient availability, temperature, and light exposure also influence whether toxin genes are expressed.
Could Cyanotoxins Persist in a Swimming Pool?
Cyanotoxins present in the context of Field Sampling of Swimming Pool “Black Algae” require further investigation.
The discovery of potentially toxigenic cyanobacteria naturally raises an important question.
Could cyanotoxins produced within biofilms pose a risk in swimming pools?
Based on existing water treatment research, the answer appears unlikely in properly maintained pools.
Swimming pools contain large volumes of water that dilute any localized microbial byproducts, and they operate under continuous disinfection conditions. Chlorine, ozone, and other oxidants used in water treatment have been shown to degrade several cyanotoxins, including microcystins.
According to the U.S. Environmental Protection Agency (EPA) guidance document Cyanobacteria and Cyanotoxins: Information for Drinking Water Systems, oxidants such as chlorine can inactivate microcystins, although the efficiency of this process is influenced by factors such as pH and contact time.
Because of these conditions, any toxins produced locally within a biofilm would likely undergo rapid dilution and oxidative degradation within a properly maintained swimming pool system.
Nevertheless, laboratory testing was necessary to determine whether microcystins were present within the collected biomass.
The implications of our Field Sampling of Swimming Pool “Black Algae” work extend to broader environmental concerns.
Laboratory Identification Methods
GreenWater Laboratories conducted the cyanobacteria screen using microscopy techniques commonly employed in aquatic microbiology.
Wet mounts were prepared from the sample biomass and examined at 100× magnification using a Nikon Eclipse Ti-S inverted microscope equipped with phase-contrast optics and epifluorescence.
Higher magnifications were used when necessary to confirm morphological characteristics of cyanobacteria.
This microscopy-based screening method allows phycologists to identify cyanobacteria genera and determine whether potentially toxigenic organisms are present within environmental samples.
Through rigorous Field Sampling of Swimming Pool “Black Algae”, we enhance our understanding of aquatic ecosystems.
Next Step: Microcystin Analysis
Because potentially toxin-associated cyanobacteria were identified during the screening process, authorization was granted to proceed with microcystin testing of the biomass samples.
However, conducting toxin analysis in samples originating from chlorinated environments presents additional challenges.
Understanding how disinfectants interact with microbial biofilms—and how those conditions influence toxin detection—became the next focus of the investigation.
The results of that analysis would provide further insight into the relationship between swimming pool cyanobacterial biofilms and potential toxin production.
Why This Matters for Pool Operators
For pool operators, Field Sampling of Swimming Pool “Black Algae” is key to effective management.
For aquatic facility managers, pool service professionals, and individuals responsible for maintaining commercial pools, research into swimming pool biofilms provides valuable insights into real-world water quality challenges.
Continuous research, including Field Sampling of Swimming Pool “Black Algae”, benefits our understanding of water quality.
Biofilm-forming microorganisms can resist treatment because the extracellular polymeric matrix protects embedded cells from disinfectants. Understanding how these communities form and behave is essential for effective remediation.
Professional education programs such as Certified Pool Operator (CPO) certification courses teach aquatic professionals how to manage disinfection chemistry, circulation systems, and microbial risks within recreational water environments.
Programs emphasizing Field Sampling of Swimming Pool “Black Algae” offer critical training for professionals.
A deeper understanding of biofilm microbiology helps operators make informed decisions when addressing persistent surface growth and maintaining safe swimming conditions.
Take the Cerified Algae Prevention & Eradication Specialist Ondemand Class
Related Articles in This Research Series
The importance of Field Sampling of Swimming Pool “Black Algae” in ongoing research cannot be overstated.
The Black Algae Myth
Not All Black Algae Is Created Equal
Microcystin Test Results
Useful tips. We have to be conscious before choosing a pool for swimming.
Thank you for reading! You are correct, bathers should always “look before they leap”. To minimize risk: Always a visual inspection; Ask to see the Pool Operater’s Certification (so we know that the pool is maintained by someone who is properly trained and Certified); take a look at the most recent inspection report, in most jurisdictions this info is available online: https://waterandhealth.org/healthy-pools/swimming-pool-inspection-reports/
I can’t even imagine what is growing in my pool right now, post Hurricane Michael. Mitigation/clean out is not scheduled yet due to the high volume of need! I could have a car in the deep in right now and not even know 🙁
Thank you for reading! I know that the pool pros in your area are working feverishly to gain ground, as is everyone in their efforts to recover. The panhandle and all throughout the Southeast that were in Michael’s path remain in our prayers. ?