Why Is My Hot Tub Water Turning Green?

Green water is usually caused by algae growth. Shock the water, clean the filters, and adjust the sanitizer levels to eliminate the algae.

What Causes Green Hot Tub Water?

If your hot tub water is turning green, it’s important to first understand what’s causing the problem. Green water is typically caused by the presence of algae, although it can also be linked to other water quality issues.

Algae Growth

One of the most common causes of green water is the growth of algae. Algae thrives in warm, moist environments, and hot tubs provide the perfect conditions for it to grow, especially if the water isn’t properly balanced.

• Signs of algae growth: Green water, slimy walls, or floating algae clusters are all indicators of algae growth in your hot tub.
  

• Cause: Algae can enter the hot tub through open covers, swimmers, or even from untreated pool or spa equipment.
  

Algae can grow quickly if left unchecked, so it’s important to act fast. Once algae starts growing, it can rapidly take over the water, making it difficult to restore clarity without a lot of effort.

High Levels of Copper or Iron

Another potential cause of green hot tub water is the presence of metals like copper or iron. These metals can come from your water source, plumbing, or even certain pool chemicals.

• Signs of metal buildup: Green or blue-green water, especially after adding chemicals, can be a sign of high metal content in the water.
  

• Cause: Copper can turn water green, while iron can cause rust-colored water. High levels of these metals can stain surfaces and make the water appear cloudy or discolored.
  

When metals like copper are present in high amounts, they can interfere with your hot tub’s chemical balance, leading to green water and possible stains on the tub’s surfaces.

Improper Water Chemistry

If the water chemistry in your hot tub is out of balance, it can cause various issues, including green water. When the pH, alkalinity, or sanitizer levels are incorrect, it creates the perfect environment for algae and other microorganisms to flourish.

• Signs of poor water chemistry: Green water, along with skin irritation, cloudy water, or an unusual smell, can indicate improper water chemistry.
  

• Cause: An imbalanced pH or low sanitizer levels (such as chlorine or bromine) can contribute to algae growth and other water quality problems.
  

Water chemistry plays a key role in keeping your hot tub water clean. Without proper balancing, it can make it harder for your sanitizing chemicals to do their job, leading to cloudy, green water.

Dirty or Clogged Filters

Filters are responsible for removing debris and contaminants from the water. When they become clogged with dirt, oils, or organic material, they can’t perform their job effectively, leading to water quality issues, including green water.

• Signs of clogged filters: If your hot tub water is cloudy or green and you notice that the filter is dirty or hasn’t been cleaned in a while, it could be a cause.
  

• Cause: A clogged filter prevents proper water circulation and filtration, which can lead to algae growth and other water quality problems.
  

A dirty or clogged filter can impede the flow of water, allowing contaminants and algae to accumulate. Regular maintenance and cleaning of your filter are necessary to prevent these issues.

How to Fix Green Hot Tub Water

If you’ve noticed that your hot tub water is turning green, there are several steps you can take to restore it to its clear, inviting state. Here’s how to fix green hot tub water:

1. Test the Water Chemistry

Before you start cleaning or adding chemicals, it’s important to test your hot tub water to see what’s going wrong. A water test kit will help you check the pH, alkalinity, and sanitizer levels.

• Test the pH and alkalinity: Ensure the pH level is between 7.2 and 7.8, and the alkalinity is between 80 and 120 ppm.
  

• Test sanitizer levels: Ensure that your chlorine or bromine levels are within the recommended range. If the sanitizer level is too low, algae can thrive.
  

• Adjust the levels: Use pH balancers, alkalinity adjusters, or sanitizer to bring the water chemistry back into balance.
  

Testing the water will give you a clear idea of where adjustments are needed. This step is essential for restoring the proper balance and preventing future algae growth.

2. Shock the Water

Shocking the water is one of the most effective ways to kill algae and bacteria. Pool shock products, like chlorine shock or non-chlorine shock, are designed to eliminate organic contaminants in the water.

• Choose the right shock: If you suspect algae growth, use a chlorine-based shock treatment. If you’re dealing with high metal levels, consider using a metal sequestrant.
  

• Add the shock: Follow the manufacturer’s instructions for the correct amount of shock to add to your hot tub. Run the jets for a few hours after adding the shock to help circulate it through the system.
  

• Wait for the shock to work: Allow the shock treatment to work for at least 24 hours before checking the water clarity.
  

Shocking the water helps to kill off algae spores and any bacteria present in the water, clearing up the green discoloration.

3. Clean the Filters and Jets

Clogs in the jets or filters can restrict water flow and cause the jets to stop working. To fix this issue:

• Turn off the power: Ensure the power is off before cleaning.
  

• Remove the filter: Take out the filter and rinse it with a hose to remove any dirt or debris.
  

• Clean the jets: Use a small brush or pipe cleaner to remove any debris from the jets. If there’s mineral buildup, use a cleaner designed for hot tub jets.
  

• Replace the filter if needed: If the filter is damaged or overly dirty, it’s time to replace it with a new one.
  

A clean filter ensures that water is properly filtered and circulating, preventing the buildup of contaminants and keeping the water clear.

4. Add a Metal Sequestrant

If high levels of copper or iron are causing the green water, adding a metal sequestrant can help bind the metals and prevent them from causing further discoloration.

• Use a metal sequestrant: Look for a product designed to remove metals like copper and iron from hot tub water. Follow the manufacturer’s instructions for the correct dosage.
  

• Add the product: Pour the metal sequestrant directly into the hot tub water and run the jets for a few hours to help circulate the solution.
  

A metal sequestrant binds with the metals in the water, allowing them to be filtered out and preventing them from staining your hot tub’s surfaces.

5. Clean and Sanitize the Hot Tub

Once the algae and metals are dealt with, it’s time to clean and sanitize your hot tub to ensure the water is safe and clear.

• Wipe down the surfaces: Use a non-abrasive cleaner to wipe down the surfaces of the hot tub, including the walls, seats, and jets.
  

• Clean the jets: Use a jet cleaner to flush out any remaining algae or debris from the plumbing system.
  

• Test the water again: After cleaning and adding chemicals, test the water again to ensure it’s properly balanced.
  

Proper cleaning and sanitization ensure that your hot tub is both clean and safe to use.

6. Maintain Regular Water Care

Once the green water issue is resolved, ongoing maintenance is essential to keep your hot tub water clear and healthy.

• Test the water regularly: Test your water at least once a week to ensure the pH, alkalinity, and sanitizer levels are within the proper range.
  

• Use a cover: Cover your hot tub when not in use to prevent debris from falling in and to keep the water clean.
  

• Clean the filters: Clean the filters regularly, ideally once a month, to keep your hot tub functioning properly.
  

Regular maintenance is the best way to prevent green water from returning and keep your hot tub water clear and inviting.