Does It Matter What Types of Swimming Pool Algae You Have

If you are a pool owner then sooner or later you are going to have a chemical problem with your pol’s water especially when the summer’s weather changes from warm to hot and the pool’s occupants go your kids to their friends and few pool parties then you wake up one Monday morning with algae in your pool. Does it matter what type of swimming pool algae you have?

No, Green, Yellow & Black are all treated the same

Balance H2O Chemistry
Scrub & brush the pool’s walls and floor
Run filter 24 hrs.
Super-chlorinate to 8ppm+
Use an algaecide 2-3 days after shocking
Use a Flocculant
Vacumn to waste
Increase Maintenance
Bump chlorine residual in between your shocking schedule

Some Algae are tougher to kill than others but all are controlled with (disinfectants like chlorine and treatments like algacides) and will find a way to survive in your swimming pool no matter what the residual is especially in spots where they can hide like cracks or crevices where colonies can set up and make a home and as soon the pool water is to their liking can explode and populate.

Identifying Types of Pool Algae in Your Pool and Spa


Identifying types of pool algae in your swimming pool and spa is crucial for effective treatment and prevention. Common types include

  • green algae, which can make the water appear green, and murky
  • yellow or mustard algae, often found on pool surfaces, and steps
  • black algae, recognized by its dark green or black spots that adhere to pool surfaces. Proper identification allows pool owners to implement targeted and efficient algae treatments, ensuring a clean and clear swimming environment.

The word ‘algae’ may bring to mind a singular image or concept, but there’s more to it. Several different types of algae can bloom or create a slimy mess in your swimming pool.

Green algae are the most common type of pool algae. It can spread rapidly, turning pool water into green, murky slime. When we’re talking about green algae, it’s important to pay attention to your filters. You’ll notice that low chlorine levels often accompany this form of swimming pool algae. As such, its prevention revolves around maintaining chlorine levels of 1-3 ppm or parts per million in the water.

On the other hand, black algae pose the greatest challenge to pool owners. Unlike green algae, black algae firmly attach to the pool surfaces, making it harder to get rid of them even with vigorous brushing. Maintaining a clean filter and having powerful pool pumps can assist in its prevention. If it manages to establish itself in your swimming pool, stronger chemicals or special cleaners may be necessary.

Yellow algae are less common, but they’re not less troublesome. They are usually found in parts of the pool that do not get much sunlight or have stagnant water. Shocking the pool with high levels of chlorine can rid the pool of yellow algae, but like black algae, you might need specific chemicals to deal with it effectively.

Treatment and maintenance strategies for each are the same. For green algae, you can manually vacuum and scrub the pool, run the filter continuously until the water clears, and maintain the chlorine levels.

The approach to dealing with black algae includes brushing the pool (preferably with a stainless-steel brush), shocking the pool water with high doses of chlorine and algaecide, and running the filter pump to remove dead algae. For yellow algae, routine shocking with chlorine and thorough brushing should be combined with algaecide treatment and periodic filter cleaning.

The best course of action for all algae involves regular pool maintenance, such as keeping your pool’s pH level between 7.2 and 7.8, ensuring your filter is in good condition, and testing chlorine and salt levels regularly.

Combatting Black Algae: Tips for Pool and Hot Tub Owners


The type of algae found in your pool or hot tub can determine your approach to maintenance and cleaning. It’s more than just the swimming pool’s aesthetics that are affected it can damage your pool equipment

Algae can significantly impact the parts of your pool system, like the heater, filter, and spa heaters. Understanding the type of swimming pool algae you’re dealing with is thus crucial, as not all types can be effectively fought with a simple algaecide treatment.

Green algae is the most common type of algae found in swimming pools. This type of algae finds it easy to open shop on a pool surface, particularly when chlorine levels are low. You can usually find green algae floating freely in the pool, but it can also cling to the pool surface.

To get rid of green algae, your algaecide of choice should contain a mix of chlorine and a good type of broad-spectrum algaecide. Pool owners must also make sure to balance the level of chlorine in the pool as part of routine pool maintenance.

The black algae, however, is the toughest to handle and invades swimming pools and hot tubs differently than green algae. Black algae usually appear as small black spots on the pool surface but tend to extend roots into the pool’s plaster, which makes it very difficult to eliminate. Regular pool cleaning tools alongside algaecides formulated to combat black algae are particularly useful here.

Combatting black algae in pools and hot tubs can be challenging, but with the right approach, it’s manageable. Here’s a list of tips for pool and hot tub owners dealing with black algae:

  1. Identify Black Algae:
    • Recognize the distinct appearance of black algae, often forming dark green or black spots that adhere firmly to pool surfaces.
  2. Brushing and Scrubbing:
    • Vigorously brush and scrub the affected areas with a stiff pool brush to disrupt the protective layer on the algae and expose it to treatment.
  3. Vacuuming:
    • Use a pool vacuum to remove dislodged black algae and prevent its spores from spreading to other areas of the pool.
  4. Shock Treatment:
    • Apply a strong shock treatment with a high dose of chlorine to kill the algae. Repeat the shock process as needed, following manufacturer guidelines.
  5. Algaecide Application:
    • Use a specialized algaecide formulated to combat black algae. Follow the product instructions carefully and apply directly to affected areas.
  6. Scrubbing Tools:
    • Utilize specialized scrubbing tools, such as algae brushes or pumice stones, to target and remove black algae from pool surfaces.
  7. Maintain Proper Water Chemistry:
    • Ensure proper water balance and chemistry, including pH levels and adequate sanitizer levels, to discourage algae growth.
  8. Sunlight Reduction:
    • Consider using a pool cover or reducing sunlight exposure to inhibit the growth of black algae, which is more resistant to UV rays.
  9. Frequent Testing:
    • Regularly test and monitor pool water parameters to address any imbalances promptly and prevent conditions favorable for black algae growth.
  10. Professional Assistance:
    • If black algae persist, seek assistance from pool professionals who can provide expertise and recommend advanced treatments.

Combating black algae requires persistence and a multi-faceted approach. By combining proper maintenance, targeted treatments, and preventive measures, pool and hot tub owners can effectively manage and eliminate black algae infestations.

in avoiding any form of pool algae in your hot tub. Regular upkeep in terms of scrubbing, filtering, and balancing the chemicals in your pool goes a long way.
While your pool filter helps remove physical debris from the water, heater spare parts maintenance ensures the continued performance of your pool’s heating system. Every pool owner has a unique spa view toward pool maintenance, but one thing remains consistent the need to keep your pool clean and safe.

Regular maintenance on your pool is very important. It keeps your pool looking good, extends the lifespan of your pool’s installation like pool surface, spa heaters, and filters, and ensures the continued enjoyment of your private retreat. A balanced pool and Chlorine will kill any kind of algae regardless of the color, some more stubborn ones need more treatment. Prevention is the best treatment.


Common Types of Green Algae in Pool Water

 Common Green Pool Algae

Coccoid green alga. Unicellular Green Alga, 100X at 35mm. Very common... | Microscopic photography, Biology art, Green algae
Unicellular Green Alga, 100X

The most common and easily recognized of the main types of algae is green algae. Recognizable by its bright green color, this type develops in three stages: teal, dark, and black green. No matter the stage, this algae spreads fast and will coat a pool in a slimy, slick film. Luckily, green pool algae are the most common in pool water and the easiest variety to kill because their the easiest to spot.

Green algae is a common issue in pool water and can manifest in various forms, each requiring specific treatment. The most prevalent types include:

  1. Planktonic Green Algae: These microscopic algae cause the water to appear green and hazy and can be treated with algaecides and proper filtration.
  2. Filamentous Green Algae: Known for forming long, stringy masses on pool surfaces, filamentous algae can be brushed and vacuumed, and shock treatments are often effective in their removal.
  3. Green Spot Algae: Typically found on pool surfaces and equipment, green spot algae can be scrubbed off manually, and maintaining proper water chemistry helps prevent its recurrence.
  4. Mustard or Yellow-Green Algae: Often mistaken for sand or dirt, this chlorine-resistant algae requires shock treatment and brushing to eliminate, along with adjusting and maintaining chlorine levels.
  5. Green Water Algae: Giving the pool a cloudy green appearance, this type is usually a result of inadequate sanitation and can be treated with shock, algaecides, and improving circulation and filtration.

Identifying the specific type of green algae is crucial for implementing an effective treatment strategy in pools.

The higher temperatures and Bather loading during these summer months can bring inconsistency in a pool’s sanitizer levels, and algae can rear its ugly head. Algae is a single-celled plant form. It uses the process of photosynthesis to manufacture its food. It comes in a very wide variety of colors and forms, making it adaptable to almost any condition.

Due to algae’s microscopic size, it takes millions of these plants to accumulate to be noticed by the naked eye! By that time it may be too late and very costly to correct.  As we tell all our customers: The best way to do away with any kind of algae is through prevention!  Green algae can grow to the wall ladders or float in the water. Get rid of it by brushing the pool, shocking, and adding Algaecide 60 to a schedule especially in the summer whether you need it or not.

Tackling Mustard Algae in Your Swimming Pool Water


Yellow Pool Algae

Those bright spots gathered around the walls of your pool are yellow, or mustard, algae. This type of algae is rare, typically only appearing in humid climates and sticking to shadier corners and edges of your pool. This algae lacks a certain pigment, which causes them to appear lighter in color. But they are still Algae. 

They usually form in small colonies of only a few cells. Yellow algae grow slower than the others but being somewhat chlorine resistant, it is difficult to get rid of, and it may take multiple attempts to fully rid it from your pool.

A close relative to green algae, mustard algae can be yellowish, yellow-green, or brown and is typically slimy. Commonly mistaken for dirt or sand, mustard algae will persistently cling to pool surfaces, light fixtures, wall fittings, ladders, and other items, like toys floating in the pool or bathing suits.

Mustard algae is typically found in warmer regions, but it can grow in any pool or spa. Unfortunately, mustard algae is common and without proper water care, any pool or spa surface can be a home to it.

Tackling mustard algae in your swimming pool water requires targeted efforts to eliminate and prevent its recurrence. Here’s a small list of steps to effectively handle mustard algae:

  1. Identify Mustard Algae:
    • Recognize mustard algae, often appearing as yellowish-brown or mustard-colored spots on pool surfaces, which can be easily mistaken for sand or dirt.
  2. Brush and Scrub Surfaces:
    • Vigorously brush and scrub the affected areas to break the protective outer layer of the algae, making it more susceptible to treatment.
  3. Shock Treatment:
    • Administer a shock treatment with a high dose of chlorine to kill the algae. Ensure that the shock treatment is specifically designed for mustard algae.
  4. Maintain Proper Chlorine Levels:
    • Keep chlorine levels within the recommended range to prevent mustard algae from returning. Regularly test and adjust chlorine levels as needed.
  5. Algaecide Application:
    • Use a specialized algaecide formulated to target and prevent mustard algae. Follow the product instructions carefully for application and dosage.
  6. Filtration and Vacuuming:
    • Enhance filtration and vacuuming to remove any remaining algae particles in the water. Ensure proper circulation to prevent stagnant areas.
  7. Backwash and Clean Filters:
    • Backwash and clean the pool filters regularly to maintain efficient water circulation and filtration, preventing algae growth.
  8. Preventative Measures:
    • Consider using a maintenance algaecide to provide ongoing protection against mustard algae. This is especially important in areas prone to algae outbreaks.
  9. Check and Adjust pH Levels:
    • Monitor and adjust the pH levels of the pool water to ensure they are within the recommended range, creating an environment less favorable for algae growth.
  10. Consult Pool Professionals:
    • If mustard algae persist despite efforts, seek advice from pool professionals who can provide insights and recommend advanced treatment options.

By diligently following these steps, pool owners can effectively tackle mustard algae and create a cleaner, safer swimming environment. Regular maintenance and proactive measures are key to preventing the recurrence of mustard algae in pool water.

Since mustard algae is chlorine resistant, it can be more resilient to get rid of once it finds a home in your pool or spa. It is important to address mustard algae immediately because it can quickly transfer from pool surfaces to toys, floats, and bathing suits. While mustard algae can be brushed or knocked off, you’ll want to treat it correctly to ensure it doesn’t come back.


Black Pool Algae (Blue-Green Algae) Growth on Walls

Lastly, the third type of pool algae is black, a breeding ground for harmful bacteria. As the very worst type of pool algae, black algae can seep into the concrete and cause structural damage to your pool if left untreated for a long period. Growth of black forms of algae on Surfaces varieties of algae types on pool surfaces.

When you see pools that have been let go for long periods that’s when you’ll see black algae spots on the surface of the pool structure (walls and floor) the liner or concrete. It will begin as black dots scattered across the pool floor and pool corners before spreading rapidly across the rest of the pool. But they are still Algae.

Black pool algae, often referred to as blue-green algae, is a stubborn and unsightly problem that commonly forms on pool walls. Recognized by its dark color and resilient structure, black algae roots itself into pool surfaces, making it challenging to eradicate. Treatment involves aggressive scrubbing, targeted chemical applications like algaecides, and maintaining optimal pool chemistry to prevent its recurrence.

Blue or green algae is the most common type of pool algae, but it is no less difficult to clean. Green algae cling to the walls of your pool, but can also be free-floating which creates a murky, swamp-like film over the pool water. You guessed it you’ll need the good ole’ long handle pool brush and some borax.

In the same way that baking soda can be a spot treatment for black algae, household borax does the same for blue and green algae. Simply use the borax to scrub away algae that are sticking to your pool walls and floor, then use the brush to knock it off. Follow up by vacuuming up the rest. You will have a much easier time once the borax has stopped the algae from growing.

If you encounter black algae, you’d better roll up your sleeves because you have some scrubbing to do. Grab a brush and some baking soda. Bicarbonate, is the active ingredient in baking soda, is an effective spot treatment to help kill the algae and loosen it from the wall.

Make sure you get every last particle free; black algae has particularly long and stubborn roots which makes it a stubborn strand. With enough scrubbing, you can rid the black algae for good.

In the end, all types of Pool Algae are plant life, regardless of their color. Balance your Pool Water Use an Algaecide and Shock your pool water weekly to kill this microscopic plant life before they get going.

How to Keep Algae Out of Your Swimming Pool > Pool Pal pool algae clean

What Happens When You Pee in the Pool?

  • Pee contains uric acid
  • It comes in contact with Free Chlorine in Pools
  • Reacts forming Chloramines & harmful disinfection by-products
  • like Trichloramine & Cyanogen chloride
  • Studies say Up to 8-20 gal. of urine in Public pools
  • 2-3 gals. in backyard pools, according to a study by the University of Alberta .……………………………………………………………………… Read more

Treatment Strategies for Common Pool Algae Types: Spa-Hot Tub-Swimming Pool

Effective treatment strategies for common pool algae types involve a combination of preventive measures and targeted interventions. For green algae, such as planktonic or filamentous types, shock treatments, algaecides, and diligent brushing can help eliminate and prevent growth.

Yellow or mustard algae often require shock treatments, specialized algaecides, and meticulous cleaning to address its chlorine-resistant nature. Black algae, identified by its dark spots on pool surfaces, demands aggressive brushing, high-dose shock treatments, and algaecide application, along with maintaining proper water balance.

Regular pool maintenance practices, including consistent filtration, adequate circulation, and routine water testing, contribute to a proactive approach to preventing algae outbreaks. Consulting with pool professionals for guidance and considering preventive measures like using algaecides can further enhance the effectiveness of algae treatment strategies.

Calcium hypochlorite shock, or Cal-hypo shock, is an effective algae treatment. Follow the package instructions to determine the dose for your pool size, then multiply that by two, three, or four depending on which type of algae is in the swimming pool.

For an isolated algae bloom, use granular chlorine to treat it. You can also get a brush, apply algaecide to the water, and scrub. If you have free-floating algae, you’ll have to shock your pool. To start, before shocking balance your pool water to get your pH between 7.1 and 7.3.

Use a pool brush to vigorously scrub any pool surfaces covered in algae, including the walls, floors, and steps. Apply a green algaecide according to the directions on the label. Let the water circulate for 24 hours, then brush the pool surfaces again. Vacuum or backwash to remove any remaining dead algae.

You’ll always have algae in your pool, but a few things can kick off an algae bloom. You could have inadequate filtration for your pool’s size or low or inconsistent chlorine levels. Bad water inadequate filtration or pool imbalance in your pool chemicals is also two big culprits.

The treatment for Green-Yellow-Black Algae:

  • Balance your pool’s Chemistry
  • Scrub and brush the walls and floor of the pool
  • Run your pool filter 24 hours a day for the next few days.
  • Super-chlorinate(make sure the FC levels are over 8ppm or above
  • Use an algaecide days after you shock your pool.
  • Use a Flocculant to settle out debris
  • Vacumn the pool bottom to waste on the filter
  • Whatever your Maintenance Schedule was increase it during these “dog days of summer”
  • Bump your chlorine residual in between your shocking schedule, especially in the late summer


JimGalloway Author/Editor



In the Swim-Swimming Pool Algae – Identify, Treat, Prevent



Does it matter what type of algae is in my swimming pool? Yes, it matters because different types of algae require specific treatment approaches. Identifying the algae type helps in implementing targeted and effective solutions.

How can I determine the type of algae in my pool? Visual characteristics and coloration are key indicators. Green algae give the water a green tint, while yellow or mustard algae appears as yellow-brown spots and black algae forms dark, stubborn spots on surfaces.

Are all algae types harmful to swimmers? While algae itself may not be harmful, it can create slippery surfaces and provide a breeding ground for harmful microorganisms. Effective treatment is essential for maintaining a safe and enjoyable swimming environment.

Can different types of algae coexist in a pool? It’s possible to have multiple types of algae in a pool. Proper testing and identification are crucial for addressing each type individually to prevent widespread and persistent growth.

What’s the best way to prevent different types of algae in my pool? Regular pool maintenance, including proper water chemistry, filtration, and routine cleaning, is key to preventing algae growth. Using algaecides as a preventive measure can also be beneficial.


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