How Do I Remove Mineral Stains from My Hot Tub?

Use a spa surface cleaner or a mixture of water and vinegar to scrub away mineral stains. Prevent future stains by using a metal sequestrant and keeping the water chemistry balanced.

What Causes Mineral Stains in Hot Tubs?

Mineral stains are commonly caused by high levels of dissolved minerals in the water. These minerals can come from various sources, such as:

• Hard Water: High concentrations of calcium and magnesium in the water can lead to the formation of scale deposits on the surface of the hot tub.

• Metal Contamination: If your water source contains metals like iron, copper, or manganese, these minerals can leave stains on the hot tub's surface when they oxidize. Metal contamination can occur due to the use of metal-based chemicals or from the water supply itself.

• pH Imbalance: Water that is too high or too low in pH can cause minerals to precipitate out of the water and form stains on your hot tub surfaces.

How to Remove Mineral Stains from Your Hot Tub

There are several methods to remove mineral stains from your hot tub, depending on the type and severity of the stains. Here are the most effective ways to tackle these unsightly marks:

1. Use a Hot Tub Cleaner or Stain Remover

There are many specialized products available designed specifically for removing mineral stains from hot tubs. These cleaners are formulated to break down mineral deposits without damaging your hot tub's surface. Be sure to follow the manufacturer’s instructions for the best results. Stain removers typically come in gel, powder, or liquid forms.

• Steps to Use a Hot Tub Stain Remover:

  • Turn off the hot tub and drain the water.

  • Apply the stain remover directly to the stained areas.

  • Let the product sit for the recommended time (usually 15–30 minutes).

  • Scrub the stained areas with a soft cloth or sponge.

  • Rinse the area thoroughly before refilling the hot tub.

2. White Vinegar and Baking Soda

If you prefer a natural solution, white vinegar and baking soda are great alternatives to commercial cleaners. These two common household products are effective at breaking down mineral buildup.

• Steps for Vinegar and Baking Soda Treatment:

  • Pour white vinegar onto a cloth or sponge and apply it to the stained area.

  • Let the vinegar sit on the stain for 10–15 minutes.

  • Sprinkle baking soda over the vinegar-soaked area. The combination of vinegar and baking soda will fizz and help lift the mineral deposits.

  • Gently scrub the area with a soft cloth.

  • Rinse the surface thoroughly with warm water.

3. Calcium Scale Removers

For stubborn calcium deposits, you may need a stronger solution, such as a calcium scale remover. These products are specifically designed to dissolve calcium buildup without harming your hot tub's finish.

• Steps for Using Calcium Scale Removers:

  • Turn off the hot tub and drain the water.

  • Apply the calcium scale remover directly to the affected areas.

  • Allow it to sit for the recommended time.

  • Use a soft scrub brush to gently scrub away the deposits.

  • Rinse the surface thoroughly before refilling the hot tub.

4. Pumice Stone

A pumice stone can be used for tougher stains, especially those caused by calcium deposits. Pumice is effective at scraping away mineral buildup without scratching the surface of your hot tub.

• Steps for Using a Pumice Stone:

  • Wet the pumice stone with water to avoid scratching the surface of your hot tub.

  • Gently rub the pumice stone on the stained areas in a circular motion.

  • Continue rubbing until the stains are removed.

  • Rinse the area thoroughly with clean water.

5. Professional Hot Tub Cleaning

If your mineral stains are extensive or if you’re unable to remove them on your own, it may be worth calling a professional hot tub technician. A professional can deep clean your hot tub, remove tough stains, and perform necessary maintenance to keep your hot tub in optimal condition.

How to Prevent Mineral Stains from Forming in the Future

Once you’ve removed mineral stains from your hot tub, the next step is to prevent them from forming again. Here are some key tips to keep your hot tub free of mineral stains:

1. Use a Water Softener

If you have hard water, consider using a water softener or pre-filter. A water softener will help reduce the levels of calcium and magnesium in your water, preventing the buildup of scale deposits.

2. Regularly Test and Balance Your Water Chemistry

Maintaining the proper pH, alkalinity, and calcium hardness levels is essential for preventing mineral stains. Test your water at least once a week and make adjustments as needed.

• Ideal pH levels: 7.2 to 7.6

• Ideal alkalinity: 80 to 120 ppm

• Ideal calcium hardness: 150 to 250 ppm

3. Use a Metal Sequestrant

If your hot tub water contains metals like iron or copper, using a metal sequestrant can help bind the metals and prevent them from oxidizing and staining the surface. This product is especially useful if you notice water discoloration or staining even after cleaning.

4. Maintain Your Filters

Clogged or dirty filters can lead to mineral buildup, so it’s important to clean or replace your filters regularly. Clean your filters every 4 to 6 weeks, or replace them annually to maintain proper water circulation and prevent staining.

5. Regular Draining and Cleaning

Regularly drain and clean your hot tub to prevent mineral buildup. A good rule of thumb is to drain your hot tub every 3 to 4 months, depending on usage. This will help keep your water fresh and prevent minerals from accumulating on the surfaces.

6. Avoid Overusing Metal-Based Chemicals

Certain pool and spa chemicals, such as algaecides and clarifiers, may contain metals that can contribute to staining. Be mindful of the products you use, especially those that contain iron, copper, or other metals that can oxidize and leave stains.

Additional Tips for Hot Tub Care

• Use a Hot Tub Cover: A cover will help maintain the temperature of the water and prevent external contaminants, including metals and debris, from entering the hot tub.

• Keep the Hot Tub Clean: Regularly clean the interior of your hot tub, including the jets, filters, and surfaces. This will help prevent the buildup of any minerals or contaminants.

• Be Aware of the Source Water: If you are refilling your hot tub with water that contains a high mineral content, consider using a pre-filter before filling the tub to help reduce mineral levels.

• Use Non-Metallic Sanitizers: Opt for non-metallic sanitizers like bromine or chlorine that do not contribute to staining.

By following these tips, you can help keep your hot tub in excellent condition and avoid mineral stains in the future.