Swimming in a pool with algae may seem harmless, but there are some health risks to consider. Algae itself is not directly dangerous, but its presence usually indicates problems with pool maintenance and sanitation. Additionally, some types of algae can cause skin irritations. Weighing the pros and cons will help determine if swimming in an algal pool is OK in your specific situation.
Quick Answers
– Algae itself is not poisonous or directly harmful to humans, but its presence indicates potential sanitation issues in a pool.
– Swimming in a thick algal bloom can cause skin rashes, allergies, or irritation in some people.
– Certain algal blooms are toxic, like blue-green algae, and should always be avoided.
– Proper pool maintenance like chlorination and filtration minimizes algae growth and health risks.
– Swimming in a pool with a mild algal bloom may be OK if you experience no irritation or health issues.
– Shower after getting out of any pool containing algae as a safety precaution.
What Causes Algae in Pools?
Algae grow in pools due to an excess of nutrients like phosphates and nitrogen compounds, as well as sunlight. Pool water contains these nutrients from substances introduced by swimmers and the environment:
- Suntan lotion
- Body oils
- Perspiration
- Urine and feces
- Fertilizers and dirt from the environment
- Decaying plant matter like leaves
With sunlight and excess nutrients, algae spores landing in the pool water can quickly grow into visible blooms. Additionally, poor pool maintenance and sanitation provides ideal conditions for algal growth. Problems like low disinfectant levels, improper pH, lack of filtration and circulation, and buildup of organic matter allow algae populations to thrive.
Types of Pool Algae
There are several common types of algae found in swimming pools:
Green Algae
The most common pool algae is green algae, which forms green spots, lines, or floating clumps in the water. It grows rapidly in the presence of sunlight and nutrients. This type attaches to pool walls, floors, rails, and equipment if not treated properly.
Mustard Algae
Mustard algae creates yellow, orange, or brown mucus-like floating clumps in pool water. It accumulates on pool surfaces and equipment. Mustard algae indicates problems with filtration and excess buildup of organic contaminants.
Black Algae
Black algae appears as black dots or smudges on pool walls and floors. It is resistant to chlorine and forms hard crusty deposits if left untreated. This type indicates insufficient sanitation and cleaning of pool surfaces.
Pink Algae
Pink algae forms pink or reddish slimy growths in pools with low chlorine levels. It adheres to surfaces and pool circulation equipment. The color comes from the reddish pigments of these algal cells.
Blue-Green Algae
Cyanobacteria or blue-green algae blooms create green, blue-green, or reddish scummy layers in stagnant water. Many species produce toxins, making blue-green algae hazardous to health. This type thrives in very warm, nutrient-rich water that is not properly filtrated or disinfected.
Is Algae in Pools Harmful?
Algae itself is not directly harmful, but its presence can indicate problematic sanitary conditions that could affect health. Potential issues include:
Skin Irritation
For some people, swimming in thick algal blooms causes itchy rashes or skin irritation. The algae cells, secretions, and cellular debris in the water can trigger allergic reactions and clog pores in sensitive skin.
Toxic Blue-Green Algae
Cyanobacteria or blue-green algae poses serious health risks as certain species produce toxins. These neurotoxins and liver toxins can cause liver damage, gastrointestinal problems, neurological effects, and other serious illness if ingested or exposed to in large amounts.
Bacterial Growth
Algae promote bacterial growth environments, as the organic matter feeds bacteria populations. Disease-causing bacteria like E. coli, salmonella, shigella, and campylobacter can potentially survive and multiply along with algal blooms.
Chloramine Formation
Chlorine mixed with nitrogen compounds from algal cells and other organic matter can produce chloramines. These irritating chemicals cause eye and skin irritation, as well as potential respiratory problems.
Swimming Impairment
Thick algal blooms can make swimming difficult and unsafe by obscuring the visibility of the water. Algal coatings can also become slippery on pool surfaces.
Benefits of Swimming in an Algae Pool
If algal growth is mild, there may be some benefits or at least lack of harm from swimming in the pool:
- Mild algal growth may not affect all swimmers. Those not prone to skin irritation may have no issues.
- Algae themselves are not toxic or directly infectious, unlike bacteria or viruses.
- Minor algal development may provide some benefits like removing trace contaminants from the water.
- Swimming may still be enjoyable if algal levels are low enough to not severely obscure visibility or coat surfaces.
- Pool water could feel soothing to skin due to the moisturizing qualities of algal cellular secretions.
- Algae growth can indicate phosphate, nitrogen, and organic matter levels are reasonably low and not at severe excess.
Risks of Swimming in an Algae Pool
Possible risks from swimming in a pool with uncontrolled algal development include:
- Increased potential for skin irritation, rashes, and allergies from algal cells and secretions
- Greater risk of infection from bacteria like E. coli that thrive alongside algae
- Possible respiratory issues from chloramines if algae is using up chlorine
- Swallowing pool water could potentially cause gastrointestinal illness
- Severe visibility issues in very thick blooms, increasing drowning risk
- Slippery and unhygienic pool surfaces covered in algal slime and biofilm
- Some blue-green algae species produce dangerous toxins that cause poisoning
Is it Safe for Kids?
Children face higher potential health risks than adults from swimming in algae-filled pools. Their lower body mass makes them more affected by toxins or contaminants. Kids are also more prone to swallowing pool water accidentally, potentially ingesting algae, bacteria, or chloramines.
High algal concentrations could severely irritate sensitive children’s skin, eyes, and mucous membranes. Young children are also at higher risk for drowning accidents if thick algal blooms obstruct underwater visibility.
However, kids are less likely to experience problems from mild algal growth than adults in most cases. Still, it’s advisable to keep pools well-maintained and minimize swimming during any algal bloom until treated.
Can You Get Sick from Swimming in Algae?
In most cases, swimming in a pool with a mild growth of green or mustard algae will not directly make you sick. But excessive algal masses indicate potentially unsanitary conditions that could lead to illness in some circumstances:
- Bacterial infections – Algae support populations of disease-causing bacteria. Ingesting contaminated water increases gastrointestinal illness risks.
- Skin infections – Cuts or scrapes may become infected if exposed to bacteria thriving in algal pools, especially if thick blooms are present.
- Sinus issues – Chloramines can irritate sinuses and cause respiratory problems from breathing air above algae-filled pools.
- Allergic reactions – Algal cells, secretions, and toxins may trigger rashes, asthma attacks, and other allergic responses.
- Toxic poisoning – Exposure to toxin-producing blue-green algae can cause severe liver damage, neurotoxicity, and even death in high enough concentrations.
Mild temporary illnesses or irritation are more likely than life-threatening conditions for most healthy individuals swimming in pools with common green or mustard algal blooms. But hazardous cyanobacterial blooms should always be avoided.
Can You Tan with Algae in the Pool?
You can get a tan from sun exposure while swimming in an algal pool, but the algae may affect the tanning process:
- Algae can form a film on skin that blocks UV rays and prevents tanning.
- Certain algal pigments may stain skin and produce unnatural discolored tanning results.
- Thick algal growth obscures sunlight penetration needed for tanning.
- Time spent away from sunlight while removing algal deposits could reduce tanning potential.
- Irritation from algal substances may require tanning cessation.
Mild algal pools will allow tanning with minimal interference. But persistent dense blooms can hinder your ability to tan due to less UV light transmission and time spent cleaning off deposits.
Will Algae Go Away on Its Own in a Pool?
In most cases, algae will not fully clear up on its own without proper remediation. The underlying factors leading to algal blooms like excess nutrients, sunlight, and poor sanitation must be addressed alongside algal removal:
- Vacuuming and scrubbing removes most visible algae, but does not treat causes.
- Cold weather or lack of sunlight only temporarily halts algal growth.
- Proper chlorine or bromine levels will begin killing algae, but some cells will survive if imbalances persist.
- Partial water draining and refilling dilutes algae, but rapid regrowth occurs if blooms are left untreated.
- Running filtration continuously removes more cells, but alone is often insufficient for full remediation.
For green, mustard, and black algae, successful removal requires filtration, thorough cleaning and scrubbing, chlorination or shocking, and often algaecide treatment. Addressing any sanitation issues is also key. Without comprehensive treatment, the algae will persist.
Is Shocking a Pool Enough to Kill Algae?
Shocking a pool with high doses of chlorine or other oxidizers will start killing algae, but is rarely sufficient on its own for complete removal. The reasons shocking alone often fails include:
- The sudden chlorine boost only kills so much algae before chlorine drops to normal levels.
- Thick algal mats protect underlying cells from full exposure to shocking chemicals.
- Algae spores can survive shocking and regrow if underlying causes are not fixed.
- Some algae like black algae have chlorine resistance and require very high doses.
- Dead algal remains still create nutrient pollution for regrowth if not removed.
- Without also addressing water balance issues, algae return rapidly after shocking treatment.
Shocking is best combined with scrubbing, vacuuming, filtration to remove dead algal debris, water balancing, and algaecide application. Using these techniques together will clear algal blooms much more effectively than shocking alone in most circumstances.
How Long After Adding Algaecide Can You Swim?
It is best to wait at least 24 hours after adding an algaecide before swimming again. Algaecides contain chemicals like polyquaterniums and copper compounds that kill algal cells. Waiting allows time for the treatment to fully work and the chemicals to become diluted in the pool from filtration:
- Quaternary ammonium compounds can cause irritation or asthma-like symptoms if swimmers enter too soon after treatment.
- Metals like copper are absorbed by algal cells during the treatment process and become less concentrated in the water over time.
- 24 hours allows all dead algal material to be filtered out, minimizing swimming issues.
- The algaecide may not have fully mixed and dispersed if you enter immediately after adding.
- Any strong chemical smell that lingers likely indicates you should wait longer before swimming.
48 hours is an even safer waiting time, as the pool water will be cleaner and any chemical residues will have had more time to dissipate. Check for any product warnings and the state of the water before deciding it’s safe to swim again after algaecide treatment.
Can You Vacuum Algae Out of a Pool?
You can vacuum some visible algae out of a pool, but vacuuming alone will not fully remediate an algal bloom. The reasons vacuuming itself is insufficient include:
- Remaining spores and cells will quickly regrow if underlying causes are not also fixed.
- Vacuuming mainly removes floating algae and some wall deposits, leaving floor growth.
- Thick mats and stubborn attached algae won’t be removed through vacuuming.
- You must also scrub walls and floors to access all algal buildup.
- Vacuuming must be done thoroughly and repeatedly to remove dead algae after other treatments.
- Hosing, netting, and flocculent may be needed for dissolved or floating algal colonies.
For best results, vacuum to remove accessible algae and debris in conjunction with shock treatment, algaecides, scrubbing, filtration optimization, water balancing, and thorough cleaning of all pool surfaces. Vacuuming can remove a portion of algae, but not eliminate the blooms on its own.
Should You Drain a Pool with Algae?
Fully draining and refilling a pool can be an effective way to eliminate algal blooms if done properly. Draining flushes out the algae, waste, and chemicals allowing fresh water to be added. However, draining alone does not always successfully treat algal growth. Considerations include:
- Draining is most effective if combined with thorough scrubbing and cleaning of all pool surfaces before refilling.
- Refilling without addressing underlying problems will likely lead to rapid algal regrowth.
- Partial draining and refilling while leaving algae still present dilutes it, but does not remove the growth.
- Draining may be require if balancing efforts or shock treatment do not resolve stubborn growth.
- Draining is not environmentally friendly and refilling uses large amounts of fresh water.
- In some regions, drain permits and codes prohibit draining pools onto public lands or waters.
Consult local regulations before draining an algae pool. While potentially effective, draining can be a last resort if proper maintenance practices are insufficient to control algal growth.
Conclusion
Swimming in a pool with minor algal growth is generally safe, but persistent dense blooms present some health risks and swimming challenges. Address the root causes of algal blooms through proper chlorination, filtration, cleaning, water balancing, and maintenance according to pool chemistry guidelines. Using algaecides and vigorous removal techniques will treat more severe algal infestations. Exercising caution and avoiding thick, widespread algal masses can allow safe swimming even with some algae present in properly managed pools.
