A swimming pool in your backyard is a good way to escape the scorching heat during summer. However, it can be frustrating when you notice the ‘pool water is clear, but the liner is green.’ It is not only very unappealing to sight but also uninviting to swim.

This is a common issue often caused by algae growth and may pose a serious health risk to swimmer health & environment. Therefore, in this article, I will help you learn the various reasons behind liner being green as well as the effective solutions to address & prevent this issue. But before I tell you all these things, let’s start with learning what causes green liner.

Pool Water Is Clear But Liner Is Green: Cause?

Pool Water Is Clear, But Liner Is Green: Cause?

According to the study conducted by Pool Spa Life, I got to know that algae growth tends to be the primary reason behind green pool liners. Since algae are microscopic plants known to thrive in stagnant, warm & nutrient-rich environments, swimming pools often make an ideal breeding ground for them.

However, you should know that if the pool water is clear but the liner is green, different types of algae can be responsible for it. Many algae grow in the pool and turn its liner green, including green algae, mustard algae, and Black algae.

Sometimes the liner also becomes green due to an imbalance in water Chemistry levels such as pH, alkalinity, or calcium hardness. If you are not paying attention to properly maintaining your pool water, it may also result in the liner being green in color.

Sometimes, lack of filtration or circulation system allows the algae to multiply and turn the liner green in color. Below I have given a proper table on the causes of green pool liners and their description.

Algae GrowthMicroscopic plants that thrive in pool water
pH Imbalance and AlkalinityIncorrect pH levels and alkalinity can favor algae
Lack of Proper FiltrationInadequate filtration allows algae to multiply
Sunlight and TemperatureWarmth and sunlight promote algae growth
Presence of Organic DebrisLeaves, grass clippings, and other debris fuel algae

Also Read: Will Stabilizer Damage Your Pool Liner?

Harmful Effects of Green Pool Water on Health & Environment

Harmful Effects of Green Pool Water on Health & Environment

You should know that green pool water is unappealing and can pose a health risk to swimmers. A study by the Centers for disease control & Prevention states that you should never step in contaminated water as it will lead to recreational water illness.

These illnesses include gastrointestinal, skin, ear, respiratory, eye, and wound infections. In addition to this, if there is a presence of algae in the pool water, it’ll also negatively affects the surrounding environment.

You should know that algae blooms consume a lot of oxygen, harming aquatic life and disrupting the natural ecosystem. Also, if you have not treated the pool water properly, algae could have found their way into your pool’s water. Below is a table of potential health risks a swimmer may experience after getting in a contaminated pool. You will also learn about the potential illness.

Health HazardsPotential Illnesses
Gastrointestinal InfectionsCaused by ingesting contaminated water
Skin and Eye IrritationsResult from contact with algae and bacteria
Respiratory IssuesInhalation of harmful airborne particles
Ear InfectionsContaminated water entering the ear canal
Wound InfectionsOpen wounds becoming infected due to bacterial exposure

Diagnosing the Issue

To effectively address the green liner of your pool water, you must diagnose the underlying problem correctly. Several factors can contribute to the discoloration of pool water, and a systematic approach to testing is crucial.

While doing my research, I learned about a study provided by the Leisure Pools USA that emphasizes regular pool water testing is critical to maintaining its clarity & safety. Therefore, ensure that you adhere to the following key parameters & testing them regularly.

ParametersAcceptable Range
pH Level7.2 to 7.8
Chlorine and Bromine Levels1.0 to 3.0 ppm for chlorine, 3.0 to 5.0 ppm for bromine
Alkalinity80 to 120 ppm
Cyanuric Acid (CYA) Levels30 to 50 ppm
Total Dissolved Solids (TDS)Less than 1500 ppm

You must pay attention to regular testing, allowing you to monitor this level and take corrective action if necessary. A too-high or too-low pH level can affect the efficacy of chlorine or bromine, leading to algae growth.

We must maintain proper alkalinity levels to help stabilize pH levels, preventing drastic fluctuation. On the other hand, cyanuric acts as a stabilizer for chlorine, protecting it from degradation by sunlight.

Ensure you are not using excessive levels of cyanuric acid, as it might hinder the effectiveness of chlorine, allowing algae to thrive. Also, make sure that you are monitoring the total dissolved solids to prevent water cloudiness caused by high levels of dissolved particles.

Related Post: Why Loose Corners in Pool Liners?

Addressing the Problem

Once you have diagnosed the issue and identified the type of algae present, it’s time to take action to restore your pool water’s clarity. First, I’ll advise you to shock your pool with a high chlorine dosage, an effective way to kill algae and sanitize the water.

This kind of process will not only help you break down chloramines but also other organic compounds, eliminating their pool source. Also, make sure you use clarifiers and algaecides, which are beneficial, especially for stubborn algae like black algae.

Also, never hesitate to brush & vacuum your pool regularly to remove any algae pores from the pool surface and prevent it from settling or spreading. Proper pool filter maintenance is also important through regular cleaning & backwashing for optimal filtration and water quality. Also, you can consider alternate methods like UV or ozone treatment, effectively reducing reliance on traditional chemical treatments.


Finding the pool water is clear, but the liner is green is a frustrating issue that needs to be diagnosed accurately & take the best course of action for appropriate treatment. I’ve given my best to give you all the information needed to know ‘what to do when pool water is clear, but the liner is green.

As of now, you know that regular water testing, proper filtration, and understanding the type of algae present are all crucial for successful resolutions. Also, make sure you take preventive measures like managing sunlight exposure by covering your pool using a pool cover when it is not being used and maintaining proper pool hygiene like showering beforehand after swimming in the pool to help prevent green liner issues in the future.

Follow all the tips mentioned and utilize proven treatment. You will be able to enjoy a sparkling clear pool that provides you with a safe & enjoyable experience for everyone. Always remember that a well-maintained pool adds value to a property and ensures the well-being of those swimming.

If you have any other concerns regarding the question, why is my pool water clear, but the liner is green? Never mind commenting below. Check my other helpful guide on pool care & maintenance shared on this website. See you in the next post, till then, take care & goodbye.