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Home / How to Get Rid of Black Algae in Pool

How to Get Rid of Black Algae in Pool

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Algae are diverse, simple plants that thrive in water. Of all the alga types and species on the planet, black algae can be the most difficult to treat and most resilient to remove from a swimming pool. Alga spores may always be present in your pool, but problems arise when the right conditions are present and the algae are able to bloom. There are ways to treat your pool and rid it of black algae, but prevention is always the best approach.

  1. 1

    Understand black algae. Like any alga species, black algae (which are really blue-green algae that look black) will grow quickly in warm water on a sunny day. Black algae are chlorine-resistant, because they have a protective outer layer that makes regular sanitization ineffective. While algae aren't harmful, their presence can be a sign that other bacteria are present.[1]

    • Other alga species that are common in pools are green algae, mustard or yellow algae, and pink algae, which is actually a bacterium.
    • Algae tend to bloom in pools that have poor circulation, poor filtration, a high pH level, and a low chlorine level.[2]

  2. 2

    Test pool levels and balance chemicals often. Chlorine should be somewhere between 1.0 and 3.0 parts per million. The pH level should be between 7.2 and 7.8. Alkalinity should be between 80 and 120 parts per million. Test these three levels once or twice a week and correct as needed.[3]

    • Calcium hardness should be tested monthly, and the ideal level is between 180 and 220 parts per million.

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  3. 3

    Shock the pool regularly. On a weekly or bi-weekly basis, shock your pool to remove chloramines (chlorine molecules that have attached to other particles) and raise chlorine levels quickly. There are four products you can use to shock your pool, and they are:[4]

    • Calcium or lithium hypochlorite
    • Granular chlorine
    • Potassium peroxymonosulfate

  4. 4

    Circulate the water. Keeping the water in your pool moving is one of the best preventative measures for algae. Not only will it make it harder for alga spores to take hold, it will also ensure that sanitizing chemicals are evenly distributed. Monitor and clean the skimmer and strainer basket regularly.[5]

  5. 5

    Clean your filter. A clogged filter won't work as well, and it will slow down the flow of water. In warmer months like July and August when algae have the best chance of blooming, run the pump for about eight hours over the course of the day.

  6. 6

    Consider using a preventative algaecide. Especially if you've had trouble with algae in the past, consider adding algaecide to your pool on a monthly basis.[6] Ammonia-based algaecides should work for green algae, but metal-based (specifically copper) algaecides are necessary for black algae.[7]

  7. 7

    Brush and vacuum your pool on a weekly basis. Brushing will remove dirt and spores, and prevent algae from taking hold.[8] Brush the walls, floor, and steps of the pool. Once you've completed your brushing, vacuum the pool to dislodge and remove any spores that have settled on the bottom.

    • Use a steel brush for concrete or plaster pools. Use a nylon brush for vinyl, fiberglass, acrylic, or painted pools.[9]

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  1. 1

    Brush the pool. Brush daily for a week with the proper brush for your pool, paying special attention to algae-affected areas. The protective layer that forms on black algae makes the algae otherwise impervious to regular sanitizers, so you must brush the algae to break through this layer so that chlorine and algaecides can kill the organism.[10]

    • Black algae have deep roots that work their way into the walls, grout, and filters in your pool. If the roots aren't destroyed, the organism will continue to grow back.
    • Try rubbing the algae spots with a chlorine tablet after brushing.

  2. 2

    Add algaecide to the water. After brushing the pool for the first time, add a copper-based algaecide that has an active ingredient concentration of at least 30 percent.[11] Aim the water return jets at the affected areas.[12]

  3. 3

    Shock the pool. After the algaecide has run its course, shock the pool. Continue your daily brushing, and after three days, shock the pool again.[13]

  4. 4

    Vacuum the pool. This will remove the dead algae and any debris that has settled on the bottom of the pool. To remove larger quantities of deal algae, consider adding an alum flocculant, which will cause the material to clump together for easier removal.[14]

  5. 5

    Clean and sanitize filters, equipment, and toys. Black algae can not only clog the filtration system and make it less efficient, but spores can also hide in the filters and bloom again when you least expect it. Wash all bathing suits and towels in the washing machine, and dry them in the dryer to kill any algae that may have attached to the fabric. Sanitize pool equipment and toys by scrubbing them with a bleach-based cleanser.[15]

  6. 6

    Test the water. You should do this regularly, but especially if you have recently adjusted the chemical levels of the pool.

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Add New Question

  • Question

    Can algae in a pool hurt you?

    wikiHow Staff Editor

    This answer was written by one of our trained team of researchers who validated it for accuracy and comprehensiveness.

    wikiHow Staff Editor

    wikiHow Staff Editor

    Staff Answer

    Algae itself isn't harmful to humans, but you still shouldn't swim in a pool with algae! This is because if algae can grow then harmful bacteria and other microbes are likely living in your pool as well and could cause a serious illness or infection.

  • Question

    Is silver-based algaecide better than copper-based for treating black mold?

    Community Answer

    Copper has ions that kill plant life; silver doesn't. While silver can destroy vegetation, copper naturally deters and inhibits growth.

  • Question

    Is black algae harmful to swim in if detected in pool before it gets treated?

    Community Answer

    No.

  • Question

    I am going to resurface the pool. Should I chip out some plaster where black algae has appeared, and if so, how deep?

    Community Answer

    Treat the algae areas by rubbing with chlorine tablets or brush in granulated chlorine with a steel brush. Apply algae code to the areas prior to scrubbing with chlorine. Pressure washing with chlorinated water prior to re-surfacing should eliminate all algae-affected areas. You have to kill the root.

  • Question

    Can I swim in the pool while it's being treated for black algae?

    Community Answer

    No, you should never swim in the pool while it is being treated with chemicals. These chemicals can be absorbed through your skin while swimming, which can be harmful. Copper-based algaecides, which are used for treating black algae, can cause staining, and can even turn blonde hair green. Handle all chemicals with caution.

  • Question

    How long after treatment with copper-based chemicals is it possible to swim in the pool?

    Community Answer

    Algae uses the chlorine treatment. When the chlorine levels return to normal, the copper algaecide has finished its work, and normal swimming may resume. Evaluate the need for additional black algae treatments for continued scrubbing and chemical additions.

  • Question

    What can I do if super shocking no longer removes blackspot algae?

    Community Answer

    Have someone go to the bottom of the pool and scrub the black algae with a Mr. Clean Magic Eraser. Then apply a good algae guard. I did this and my black algae never returned.

  • Question

    We have a salt water pool which now has black algae, and we use bromine, is this a problem when trying to rid the pool of algae?

    Community Answer

    Salt water pools are notorious for black algae, as you have no active control over the chemical levels and struggle with extremes in temperature. Use a copper sulphate solution in your pool in the off season after scrubbing. Once the algae reduces, then re-add your normal chemicals

  • Question

    Our pool is now empty, and the black algae is very hard. How can I get rid of it?

    Community Answer

    You could try an acid wash. It still may come back if the roots have penetrated the plaster, but the acid wash is your best bet.

  • Question

    I have a pool liner that has black algae spots on it. The pool is empty. What can I do to get rid of the black spots since I can't use a normal algaecide on the pool liner?

    Community Answer

    You can purchase a new liner for starters. It is probable that the one you have has shrunk. Treat the vermiculite or sand before installing to prevent algal growth.

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  • Use copper-based algaecides (and all pool chemicals) according to the manufacturer's directions. High copper levels can cause staining, and can even turn blonde hair green. Handle all chemicals with caution.

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About This Article

Article SummaryX

To treat black algae in your swimming pool, start by brushing the sides and bottom of your pool to break up the algae so it's easier to remove. Next, add a copper-based algaecide to the water and aim the water-return jets at the algae patches. After the algaecide has run its course, shock the pool by adding granular chlorine to kill the remaining algae, then shock it again after 3 days. Finally, vacuum the pool to remove the dead algae and wash the pool filters and equipment with bleach so it doesn't grow back. For more tips on how to keep black algae from coming back, keep reading!

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How to Get Rid of Black Algae in Pool

Source: https://www.wikihow.com/Get-Rid-of-Blackspot-Algae-in-Your-Swimming-Pool