Pool Care Pool Troubleshooting

How To (Quickly) Get Rid Of Pool Algae

When heading to the backyard to take a mid-day swim, one thing that can set your mind off is green pool water caused by green algae. Algae is always a frustrating thing for most pool owners, especially those living in hot areas. It does multiply quite fast and can turn your swimming into nasty green or green-yellow stuff.

Most pool owners assume removing algae from a pool is a challenging task that should only be left to professionals to fix, but that’s only partly true. It’s a process you can do yourself if you understand how the pool algae grow, why it’s in your pool, how to clean and prevent it from coming back.

So, before you lose hope in restoring your pool state, I will take you through all these and in the end, you’ll be in a better position to DIY remove pool algae out of your swimming pool.

What is Algae and What Causes It?


‘What’s is algae’ might not be a popular question since most people know it as the green matter in stagnant waters like in a pod or a dam.

Scientifically, algae is a simple, non-flowering, aquatic plant coming from many species, including seaweeds and many other single-celled plants. It contains chlorophyll but does not have any real stems, leaves, roots, and vascular tissue.

In simple English, the alga is a type of plant with no stems or leaves that grows in water or on damp surfaces. It’s merely the green, yellow or black thing you find inside a pod, wet or anywhere with stagnant water.

What causes algae?

What causes algae, on the other hand, is a common question asked by quite several people all over the internet. And to answer you, I can say that the leading causes of algae in a swimming pool are the transfer of algae spores transferred by rain, wind, contaminated swimsuits, and equipment.

When the algae conditions are right, the spores can quickly spread and take over your swimming pool in a short time. Sunlight, warm weather, poor water circulation, and carbon dioxide or nitrites in water can contribute to the rapid growth of algae. It’s close to impossible to keep algae out of your swimming pool.

So, the best defence id is creating and maintaining a hostile environment for the algae to prevent it from setting foot in your pool.

Is Algae Harmful?

According to the CDC, some harmful algae can produce toxins harmful to both humans and animals.

However, pool algae aren’t necessarily harmful to the swimmer; but they can create an unpleasant swimming environment. I don’t think anyone would want to take a swim in a greenish, slimy pool. Would you? I don’t think so!

If algae are left untreated, it can gum up the pool’s circulatory system or even damage your pool’s equipment. What’s more, pool filters aren’t built to handle algae bloom. When you run your pool filter, an algae infestation might clog up the pool filter and cause severe damage. You might be forced to replace it.

Apart from harming your pool equipment, when the algae infest your pool, it takes much energy and money to remove it from your pool. However, there is some good news. If you keep your swimming pool clean and healthy, you will avoid algae from growing and save yourself time and money.

What Types of Pool Algae Are There?

The exact color of your pool water might not be distinctive, but it will be cloudy for sure if it gets infested with algae. It can be hard to tell the type of algae taking your pool hostage. If you want to deal with the algae properly, you need to know the algae type infesting your water. For a better understanding, check the spots where the algae start to grow. Let’s take a closer look at some of these types of algae.

1. Green Algae

It’s the most commonly known algae and has the name Chlorophyta. It gets its green color from chlorophyll. The algae float in water, creating a cloudy pool and giving the water a greenish tinge. The slimy green algae attach itself to the pool walls and floors.

If your swimming pool filtration is weak or lacks ideal sanitization, the green algae growth is boosted. It can get to your swimming pool via swimwear, kids’ toys, or other items that have been used in natural bodies with water containing algae.

2. Yellow Algae

Yellow Algae or Mustard algae has a look similar to pollen or sand. If you see any of these in a shady corner inside your pool, you likely have yellow algae. It’s also referred to as mustard or brown algae. It’s a rare type and not as slimy as the green algae. Some bad news is, it’s chlorine resistant making it tough to treat.

3. Black Algae

The last type is the black algae. It’s technically a cyanobacterium and not real algae. What’s more, it’s a nasty pool infester that makes its foods. That means it never stops growing. What’s more, its strong roots can dig into concrete surfaces. That makes it tough to kill. It does grow back quickly when the treatment isn’t aggressive enough. You need to ensure that even the roots are destroyed.

What are the symptoms of Algae in Your Pool?

Although you might not see any floating lily pads on your pool’s surface, you may still have a plant problem. Algae is a nasty thing that can find its way to your swimming pool in several ways. Algae spores can be transferred to your pool water with a swimsuit, a small patch of slime on the pool float, or a piece of equipment.

If you don’t maintain balanced water chemistry in your pool, you will also be inviting algae in your pool water. When introduced, you need to get rid of it as fast as you can.

Although the pool algae aren’t harmful to swimmers, they cause cloudiness that gets thick when you can’t see well underwater. They are also food to some bacteria, so keep them off your pool water. Another thing, muddy pool water isn’t inviting at all –it’s gross.

The most common symptom of algae is discolored pool water with a greenish substance floating on the surface. However, this depends on the type of algae infestation your pool has. The water can be greenish, blue-black, or yellowish –something nasty.

Another sign is a residue of any colors in the pool corners, around the skimmers and jets, on the pool walls and around the stairs. The algae tend to be smart –it grows in crannies and nooks where it’s not easy to see it until it’s too late.

You might also get yellowish stains formed on pool surfaces that aren’t easy to get rid of. They are caused mainly by mustard or black algae. You can identify the algae stains if they cannot get off with a simple brushing.

What is the best way to get rid of algae in your pool?

Algae isn’t something I would love to see a pool owner dealing with. It’s a messy and nasty problem that wastes your time and money. However, without a proper clean, you might never get rid of it completely. Here I will introduce you to some of the best ways to remove algae in your swimming pool.

1. Manual Vacuuming

The first and, of course, the best way to deal with algae is manual vacuuming. Why? Automatic and robotic cleaners deal with small pool dirt and grime but are not suited for cleaning algae. What you need to do here is use a manual pool vacuum and clean directly to waste. Make sure you bypass your filter and prevent any recirculation of the contaminated water. While vacuuming manually, pay closer attention to the areas with algae.

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2. Brush it off your pool

Use the stiff pool brush on the telescoping pole, brush your pool wall and floor. You also need to pay close attention to the shady areas and corners where algae try to hide and grow. As you brush it ways, the water will become cloudy, that it obstructs your view. So, start with the tight spots first.

When you scrub the algae off, your pool’s walls and floors allow the pool sanitizer to get deeper into any remaining algae killing it. Brushing also stirs up the sediment brushed off for easy killing and filtering.

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3. Test and Balance the Water

The many ways you can test your pool water for pH and alkalinity. You can use a digital kit, a liquid kit, or test strips. Balancing your pool water chemistry will ensure your sanitizer works efficiently against algae. Low alkalinity or high pH can inhibit your efforts to shock your pool water. Ensure the water pH is around 7.6 and 7.8 before shocking it.

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4. Give a Shock Treatment

I’ve touched on this in tip #3. Shocking involves increasing the amount of Chlorine in the water for a while to kill bacteria and algae. That is necessary when you’re pool is infested with more resistant algae types. It’s an aggressive treatment ideal for massive infection.

The best way to shock your pool is to use pool shock treatment and a lot of it. Here you need to follow the package instruction and determine the ideal dose for your swimming pool size. I recommend you multiply that by 2, 3, or 4, depending on the damage size and the algae type in your pool water.

For the green algae, you need to multiply the dosage by three, by three, for the yellow or dark green algae and four for the black algae. Never use stabilized Chlorine to shock an algae-infected pool. Using it creates more cyanuric acid that inhibits sanitizer and allows the regrowth of algae.

You can also put your cleaning equipment in the shallow end as you shock the pool water to sanitize them too.

Pro Tip: Remember to always shock your pool at night or dusk. Why? When you shock it during the day, the sun eats up most of your Chlorine before it gets to kill the algae.

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5. Filter the brushed and killed algae out

After all the brushing and the shocking, the killed algae fill the pool with a cloudy blue thing that needs a solution. What you need to do now is run your pool filter continuously and for a minimum of 8-hours until your water clears up. You might also need to add a pool clarifier to speed up the process. Check if you need to fill up the pool water before turning on the pool pump.

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6. Test Your Water Again

Once the cleaning is done, the next step is to do retest the water. You can use the usual testing methods or water sampling services in your local pool store for a better analysis. It would be best to ensure the water chemistry is well balanced and the chlorine level is ideal before anyone can get in the water.

7. Deep Clean Your Filter

Lastly, you will need to deep clean your filter. What do I mean? The last thing you need is a pool filter filled with algae spores that can get back to your swimming pool and bring back the same problems again. Deep cleaning the pool filter by soaking it inside a diluted muriatic acid can be the best idea. You can also decide to replace it.

How Do You Prevent Algae From Growing in Your Pool?

At this point, you already know what an alga is, its symptoms in your swimming pool, and ways to get rid of it. Right? I want to introduce it to you next to prevent it from growing in your pool again.

If this is your first time dealing with algae, don’t worry, you’re not alone. Nearly all pool owners get to deal with algae problems at one time. Even when the pool filtration system is working correctly, sanitizer levels are maintained ideally, and keeping an eye on hotspots and algae can still develop.

As I mentioned a couple of times now, algae spores can find their way in your pool through any means. However, the most common and uncontrollable is rain, wind, and dirt. The best thing you can do here is make sure the algae spores never grow into algae blooms. Maintaining clean, algae-free pool water will reduce damages, keep your family safe, and keep your pool with its inviting touch.

Here are recommended ways you can prevent and eliminate algae from your pool:

1. Keep your circulation system running properly

One of the best ways to keep your pool water clean and free of algae is to ensure that your pool circulation system works correctly. You must give your skimmer(s) and pool pump strainer baskets a checkup and clean them regularly for this to happen. It allows the water and your sanitizer chemicals to flow freely and evenly throughout the swimming pool.

Alongside cleaning the pump strainer basket and the skimmer(s), it’s crucial you clean or backwashes the filter. Over time the filtered dirt and debris can clog your filters – give it simple regular backwashing. However, the cleaning can differ depending on the type of pool filter you’re using.

If you have a sand or D.E filter, then use the instruction given by the manufacturer to backwash it. It would be best to do the backwash whenever the pressure gauge reads something between 8-10 PSI, which is higher than the standard value. For the cartridge filter, clean the cartridge(s) correctly. Ensure no dirt or debris is left behind.

Use the best filter cleaners to get the most out of your filter, something like Sand Filter Revitalizer, Spray & Rinse, Cartridge Cleaner, and Degreaser. These cleaning aids can make cleaning a breeze. They can also help keep the pool filter working all season, ideally long.

It would be best to run your pool pump and filter between 6-8 hours a day during the swimming season. You may also increase this cycle to 10-12 hours when your swimming pool receives heavy usage. Check and clean your skimmer, pool pump, and filter to help keep your swimming pool clean and free of algae.

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2. Keep the pool sanitizer within the desired range always

Algae spore is the start of these algae problems, and them getting to your pool is relatively easy. The good news is, they are usually killed by Chlorine and other sanitizers before they can grow into blooms. When the sanitizer is low, the algae spores multiply and start to cling to your pool walls and floor.

If your pool uses Chlorine as the sanitizer, the levels should be between 2.0 and 4.0 ppm (parts per million). And to help maintain a safe and effective chlorine level, I recommend using an automatic floating chlorinator. This type of chlorinator feeds the pool water with a constant amount of Chlorine, preventing the chlorine level from dropping under the adequate level.

If you’re using another sanitizer, you still need to keep the levels ideal. You can also come across automatic sanitizer for other pool sanitizer types.

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3. Perform Weekly Shock

Another method I know to work in eliminating and preventing algae is shocking the swimming pool weekly. Your pool might look clear, but the algae spores might be taking residence and surprise you one day with a greenish float. The shocking can handle any algae blooms and algae spores that the sanitizer might have missed.

You can use pool shocks such as Shock Treatment or a granular chlorine shocker such as Chlorine Tablets. These two offer you the best chance to keep your swimming pool clean, level the sanitizers, and eliminate potential algae spores before they can grow.

You can also use the best non-chlorine pool oxidizer, such as Non-Chlorine Shock, as a potential pool treatment method. It helps boost the present chlorine levels and make the sanitizer more efficient at killing the algae.

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4. Create a brushing routine

Another thing you should do is create and maintain a brushing routine. Algae is familiar places in a pool area on the pool walls, floor, and steps. If you don’t brush them thoroughly, the sanitizer might not kill everything. You have to clean all these areas at least once a week or more if necessary. That will help make sure no algae grows in your swimming pool.

5. Use the right brush for your pool.

Once you’ve created a brushing routine, it’s time to find the right brush. You need something that can scrub the algae and other dirt off the pool walls and floors. What most pool owners don’t know is, the wrong brush can cause severe damage.

If you have a vinyl-lined, painted, or acrylic pool, get a nylon pool brush. The brush is softer and will never tear or scratch the pool interior. But for the concrete or plaster pools, the wire pool brush will offer superior cleaning strength enough to pluck all the algae and not harm your pool surface.

You must never use a metal wire brush on your vinyl-lined, acrylic, painted, or fiberglass pool. This type of brush is quite abrasive and can tear, scratch, or rip the pool surfaces. Also, take it easy – do not apply excessive pressure when wire brushing plaster or concrete surfaces.

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6. Vacuum to remove all the dirt and debris

Once the brushing and the scrubbing are done, you will need to vacuum your pool. It’s a fantastic way of preventing algae growth. Even though you will still need to filter the water aggressively, vacuuming ensures you collect all the algae remains and spores.

With all the brushing dislodging algae spores clinging to the surface, the spores can settle at the pool bottom. The pool circulation system might not be able to collect them. Using an automatic pool vacuum or a regular pool vacuum will ensure you eliminate anything that does not belong to your swimming pool.

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7. Use an algaecide regularly

At this point, you know what you need to do to kill and clean all the algae from your swimming water. But do you know how to ensure any algae that get to your pool is dead and never grows?

Yes, sanitizers work but not 100%. You still need to add a pool algaecide regularly. That will ensure no algae takes your pool hostage.

Algaecides are ideal for clean and algae-free pools. It’s a perfect way to stop algae spores from ever developing into full-grown blooms. And the best part is, algaecides are easy to use.

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8. Watch over your pool all year long.

Enjoying a swim in your backyard comes with a package of responsibilities. To enjoy a perfect swim means you have to maintain a pool cleaning schedule and watch any signs of algae.

That is a fantastic way to keep an eye on pool water changes. When you sustain a proper cleaning schedule, you’ll be keeping your swimming pool water clean and, at the same time preventing algae spores from growing into blooms.

While carrying out all the cleaning, make sure you watch the status of the hard-to-see areas such as the ladder and steps. If you see anything other than water, then it needs to be removed immediately.

Always take caution when using and pouring pool chemicals in the water. You should never mix the chemicals unless it’s said in the instruction. Always use the instructions in the user’s manual as provided by the manufacturer.

Related Questions

How long does it take for pool algaecide to work?

Pool algae control treatments should kill the visible green or brown film within 24-48 hours, although other forms of pool algae may require more time – up to a week. The use of your swimming pool should not be limited after one application of pool algae treatment.

About the author

Sharif Miah

Hi! I'm Sharif, the founder of Globo Pool® and I have been working in the pool & hot tub industry for the last few years. I love to share my experiences with people & hope you are enjoying my information and lessons!

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