Why is My Hot Tub Water Turning Purple?

Purple water can be caused by a reaction between high levels of manganese and chlorine. Use a metal sequestrant to prevent this issue and regularly test for metals in the water.

Common Causes of Purple Hot Tub Water

Purple water in your hot tub may appear to be a serious issue, but it’s often caused by well-known factors such as metals or imbalanced water chemistry. Below, we will look at the main causes and what can be done to resolve each.

1. High Levels of Manganese

Manganese is a metal found naturally in water, especially well water. When present in high levels, it can interact with chemicals in your hot tub, causing the water to take on a purple hue.

• How Manganese Causes Purple Water: Manganese reacts with chlorine, bromine, or other oxidizing chemicals in your hot tub, which causes it to change color, often resulting in purple or dark-colored water.

• Sources of Manganese: Wells and some municipal water sources can carry higher levels of manganese, which makes it a common culprit in many purple water issues.

• Fixing the Problem: If manganese is causing the purple color, a metal sequestrant can help bind to the metal and prevent it from reacting with your pool chemicals. Consistent water testing can help manage and prevent manganese buildup.

2. High Levels of Copper

Copper can also lead to discolored water in your hot tub. It's common in plumbing systems and can sometimes come from chemicals like algaecides or pool maintenance products.

• Copper and Purple Water: Copper interacts with high pH and alkalinity levels to create purple water, especially when combined with other metals in the water.

• Signs of Copper Contamination: Copper contamination can also cause blue or green-colored water. Stains on your hot tub surfaces may appear as a result.

• What You Can Do: Use a chelating agent to bind with copper and keep it from affecting the water. Ensure regular testing of copper levels to prevent the buildup of this metal in your hot tub.

3. pH Imbalance and Alkalinity Issues

Another common cause of purple water is imbalanced water chemistry, particularly when the pH or alkalinity is off.

• How pH Affects Water Color: If your hot tub’s pH is too high, metals like manganese or copper are more likely to precipitate, causing discoloration in the water.

• The Role of Alkalinity: Alkalinity and pH levels are closely related. If either one is too high or too low, it can cause chemical reactions that lead to purple water.

• How to Fix It: Regular testing of the pH and alkalinity levels is crucial. Keep the pH between 7.4 and 7.6 and maintain alkalinity at 80-120 ppm. Adjust these levels with pH increasers or decreasers as needed to keep the water clear.

4. Chemical Additives and Reactions

Some chemicals used in pool and hot tub maintenance can interact with other elements, leading to water discoloration.

• Potassium Permanganate and Purple Water: Certain shock treatments, such as potassium permanganate, can cause purple water when they react with metals in the water.

• Other Reactions: Clarifiers, algaecides, or flocculants can sometimes cause purple hues when mixed with metals or imbalanced water.

• Preventing Chemical Issues: Follow the manufacturer’s instructions carefully when adding chemicals to the water, and use only the recommended quantities. Rinsing off any excess chemicals after treatment will help prevent discoloration.

5. Algae Growth in Warm Water

While algae is commonly associated with green or blue pool water, purple algae can also affect hot tubs if left untreated.

• Purple Algae: Some species of algae thrive in warm, stagnant water and can turn purple or reddish. If your hot tub is not regularly cleaned or sanitized, these algae can cause the water to change color.

• Prevention: Regularly sanitize your hot tub with bromine or chlorine, and use shock treatments to kill algae spores. Proper filtration and circulation are key to preventing algae buildup.

How to Prevent Purple Hot Tub Water

Addressing purple water as it appears is important, but regular maintenance can help you prevent this issue from occurring again. Here are a few ways to keep your water crystal clear.

1. Regular Water Testing

Regular water testing is the first step in preventing purple water and ensuring your hot tub remains balanced and clean.

• Test Kit Use: Invest in a reliable water test kit that checks pH, alkalinity, sanitizer levels, and metal concentrations.

• Frequent Testing: Aim to test your water at least once a week to catch any imbalances before they turn into problems.

2. Use a Metal Sequestrant

A metal sequestrant binds to metals like copper and manganese, preventing them from reacting with your water chemicals.

• How They Work: By binding to metals, sequestrants prevent them from causing discoloration and staining in your hot tub.

• When to Use: Apply metal sequestrants when first filling your tub or periodically if you suspect high metal levels in your water.

3. Keep pH and Alkalinity Balanced

Maintaining the correct pH and alkalinity levels is essential for the overall health of your hot tub and to prevent purple water.

• Regular Adjustments: Keep the pH between 7.4 and 7.6, and the alkalinity between 80-120 ppm. These levels help prevent the precipitation of metals.

• Test Frequently: Regularly test and adjust your water chemistry to ensure the pH and alkalinity remain in the correct range.

4. Shock Your Hot Tub Regularly

Shocking your hot tub on a regular basis can help eliminate contaminants and prevent algae growth, which can lead to discoloration.

• Shock Treatment Frequency: Shock your hot tub at least once every two weeks or more frequently if you notice the water becoming cloudy or discolored.

• Choose the Right Shock: Use a chlorine or non-chlorine shock treatment to maintain clean, clear water.

5. Clean the Hot Tub Regularly

Maintaining a clean hot tub is vital to preventing purple water caused by algae or contaminants.

• Routine Cleaning: Make sure to clean the filters, check for debris in the water, and wipe down the surfaces of the tub regularly.

• Circulation: Run the pump regularly to ensure the water is circulating properly, which will help prevent the buildup of algae and metals.