How to Understand and Tackle Pool Algae

Austin Pool Maintenance Guide to Algae

Pool algae is a mostly aquatic organism. It needs water and light for photosynthesis so it can flourish. Algae spores are generally carried into your pool by the wind or rain. They can also arrive by way of dirty water, on animal fur, or even by bathers. Pool algae will always be present at the microscopic size, even in the cleanest pool.

In many pools, developed algae hide in protected areas. Surfaces include the light niche or the skimmer, where brushing never happens. If pool plaster is deteriorating, then algae can grow in the cracks or pitting. It is again protected from brushing or cleaners.

Pool Algae Growth

Algae will bloom as soon as conditions are favorable. You may have a pool with perfect water balance and one of Austin’s big storms can wash in a load of new algae spores and possibly other debris which combined with the added rainwater can change the chemistry balance of your pool and suddenly your perfect pool is now a perfect incubator for a pool algae bloom. Check out our pool safety guidelines for more information.

Favorable Conditions for Algae

When conditions are favorable for the algae, a bloom can occur, and your pool can turn green in a matter of hours.

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How Algae Affects Your Pool

The algae that you find in your pool is generally not dangerous to people or animals. It is unsightly, however, and it can create slippery surfaces and drowning risks due to a lack of visibility. Pool algae is a sign that the water chemistry is not under control. Therefore, more dangerous organisms, like E-coli bacteria, could be present.

Changes Your Pools pH

What algae does do is it creates a chlorine demand, that makes the water conditions more favorable to algae and it clogs up filtration systems, that reduce circulation and again create more favorable conditions for algae. As pool algae develop it produces carbon dioxide which can increase the pH level of the water, which reduces the effectiveness of chlorine, again making the water conditions more favorable to algae. This is why when a pool starts going bad it can get really bad really quickly.

Types of Algae

There are thousands of types of algae. From giant kelp seaweed to the microscopic picoplankton. Here are the most common types that we face in swimming pools:

Green Algae:

Green Algae is the most common pool algae. It can be free-floating in the water or growing on the walls in sheets or spots.

Mustard or Yellow Algae:

Grows on the walls and usually in areas that have less sunlight.

Black Algae:

It generally grows in spots and is difficult to get rid of completely. Black algae is so challenging because it develops extensive roots. They grow deep into the plaster, and in some cases, right through the pool plaster. If the root is not destroyed, then a new head will develop in time.

Pink Algae:

Pink Algae is actually a bacteria that grows as spots or streaks. It is typically found in corners, or in areas where brushing and pool cleaning won’t get to it.

How to Prevent Pool Algae

The key to preventing algae is meticulous pool maintenance.


Sustain the correct water chemical balance and keep the water and surfaces clean. Adequate chlorine levels at the right pH level go a long way.


Brushing the pool is essential. Many algae types have a slimy coating that protects them from the effects of chlorine. Brushing rubs away the slime coating and damages the algae surface. Thus, making it a lot more susceptible to chlorinated water.


Proper filtration is needed to maintain a good water chemistry balance. Be sure the water is moving through a functioning filtration system.

How to Get Rid of Algae


Shock the Pool with Chlorine

Generally, chlorine is the killing agent for algae, so it is important to shock the pool with chlorine. As mentioned, pool algae create a chlorine demand. If algae are already visible, then it is vital to get enough shock into the water at the first treatment. Otherwise, the chlorine gets used up before the algae are eliminated. As a result, the spent chlorine and dead algae create a more inviting environment for algae. And the problem gets even worse.


Maintain a Low pH Level

To enable the chlorine to be effective, keep the pH level at the lower end of the suitable range (around 7.2). Also, ensure that stabilizer levels are within norms (50 ppm to 80ppm). Too low and the chlorine will be destroyed by the sun. Too high and the chlorine is rendered less effective.



As algae tend to block up filtration systems, it is a good practice to backwash before adding chemicals to the pool. Then, backwash again daily until the pool has cleared up. Testing the chemicals every day is important for a green pool until the problem has cleared up. Once the algae have been killed the dead algae needs to be removed, which with regular filtration can take days to weeks to clear up completely. If the algae bloom was severe (a green pool) then once the algae has been killed it may be necessary to add a flocculant to get the dead algae out of the pool.

YardDoc Pool Services

YardDoc employees are trained to the highest industry standards and use the latest equipment and systems. This ensures you receive the level of knowledge and care required to save money while maintaining your pool.


We achieve customer satisfaction and loyalty with long term relationships, great service, consistent communication, and fair pricing. We live by our motto and guarantee: Professional Service and Personal Care.

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