why does algae grow in pools

Why Does Algae Grow in Pools: Top Causes

by | Aug 11, 2023 | 1 comment

Need to prevent algae growth in your pool? Call Clements Pool Services and Remodeling at (352) 735-4878.

Have you been wondering,” why does algae grow in pools?” There are several different causes for algae growth in swimming pools. It can seem like an endless battle to rid your pool of algae overgrowth. The most efficient option is to prevent algae from growing in the first place. Read on to find out more about the top causes of algae growth in pools from a professional pool repair and service company.

Top Causes for Algae Growth In Pools

Algae spores are common in pool water, but when algae grow uncontrolled, your pool water can turn green. Algae give the pool a slimy feeling and can also clog filters and create an undesirable environment. Some of the top causes for algae growing in pools include: 

Poor Filtration

When answering the question, “why does algae grow in pools?” the main answer is poor filtration. Failing to change the pool filter causes the pool to become susceptible to bacteria and algae growth. A lack of filtration and poor water circulation allow dirt and bacteria to build up, which feeds algae growth.  

Improper pH Levels

Improper pH levels in the pool can result in an algae bloom and turn the entire swimming pool green in a matter of hours. It’s important to test the pH of your pool water regularly using a water test kit. 

If the pH is between 7.2 and 7.6, this is a balanced pH level ideal for staving off algae. 

A water test kit can also help check the chlorine levels. Fluctuating chlorine levels are also one of the primary causes of algae growth. If the chlorine is off, try adding in more chlorine as well as a stabilizer which can maintain the appropriate chlorine levels in the pool. 


Fallen leaves, bacteria, and organic matter provide easy food for algae spores. Algae spores can also grow from the presence of carbon dioxide, nitrates, and phosphates. 

It’s essential to keep the pool clean with regular brushing and debris removal. Although it’s impossible to get every speck of dust and debris out of the pool, regular debris removal can help to minimize the spread of algae. 

Types of Algae 

There are over 21,000 different types of algae! When it comes to swimming pools, a few main types of algae are responsible for discolored water. Learning about the types of algae can assist you in your approach to tackling each one. 

Green Algae

Green algae typically affect swimming pools and create a greenish hue. This type grows in clumps or sheets and creates a slimy coating on the water’s surface. Green algae reduce water clarity and promote bacterial growth. 

Pink Algae

Pink algae is a type of bacteria that can cling to surfaces in and around the pool that the pool brush can’t reach. It shows up as small spots in cracks and crevices and grows due to an imbalance in chlorine levels. 

Yellow Algae

Yellow algae, or mustard algae, grow due to faulty filtration and improper chlorine levels. Yellow algae create sheets of slimy yellow coating and can be very difficult to eliminate. 

Black Algae

Black algae is another strain of algae that is extremely challenging to eliminate. It grows when there is insufficient sanitization and filtration. Black algae have a dark bluish-green hue and show up as small spots. It can attach to the bathing suits of swimmers who have been to the ocean or a pool with black algae and spread to your pool that way. 

How to Prevent Algae Growth in Pools

It’s much easier to prevent algae growth in pools than it is to remove it. Algae growth can become a major problem, but with a few key steps, you can avoid an algae bloom. If you have a sparkling clean pool and want to keep it that way, follow these best practices to prevent algae from growing. 

Chlorine and pH Balance

The main method of preventing algae growth is with the right balance of pH and chlorine levels. Bringing these two elements into balance will go a long way toward minimizing the spread of algae in your pool. Once you have added the right amount of chlorine, make sure to use cyanuric acid to ensure consistent chlorine levels. 

Proper Sanitation

With proper sanitation, you can reduce the chance of bacteria and algae growth in your pool. A pool’s cleanliness is directly related to the presence of organic material and bacteria which feed algae. The more often you brush and clean the pool, the better it will be to prevent algae colonies from growing. 

Improved Filtration

A lack of proper filtration in the pool can cause algae to multiply quickly. Run your filters for about 12 hours per day to keep water circulating and the pool clean. If the pool filter is too small, then the filter may need to run for an even longer time. You must make sure to change the filter on schedule. 

How to Get Rid of Algae

If algae have already overtaken your swimming pool, you will need to take measures to remove it altogether. Algae spores are very small and often wait for the conditions to be just right before exploding and blooming in a matter of hours. To get rid of an algae overgrowth, you will need to remove debris, balance the pH, and turn off the pool heaters. In a very serious case, you may need to drain the pool completely or call a professional pool care company.

Turn to Clements Pool Services and Remodeling to Keep Your Pool Algae-Free

So why does algae grow in pools, and what can you do about it? Turn to Clements Pool Services and Remodeling. We offer expert pool services, and we can help you to learn about pool maintenance signs so you can get the pool maintenance you need on time. Give us a call to learn more at (352) 735-4878 today. 

Expanding to Plymouth: Your Trusted Pool Services

Exciting News for Plymouth Residents – Clements Pools is delighted to bring our expert pool services to your neighborhood! Committed to creating and maintaining your dream pool, our expert team is ready to offer personalized, top-tier solutions for your pool’s design, construction, and upkeep. Experience the Clements Pools difference in Plymouth, where your pool’s beauty are our top priority.

About Misty Clements
Misty Clements is the owner of Clements Pool Services & Remodeling. She and her husband have built Clements Pools to be a leader in the pool industry in the Lake County area. They offer pool service, pool remodeling, pool automation, and more.