How to Remove Stubborn Stains from Hot Tub Shells

Keeping your hot tub clean and free of stains is essential for both aesthetics and hygiene. Over time, hot tub shells can develop stubborn stains from minerals, oils, algae, and other contaminants. If left untreated, these stains can become harder to remove, making regular maintenance crucial.

This guide will walk you through the best methods for removing stubborn stains from hot tub shells and how to prevent them from returning.

Common Causes of Stains in Hot Tubs

Stains in your hot tub can result from several factors:

Mineral Buildup – Hard water with high levels of calcium and other minerals can leave white or chalky stains.
Algae and Organic Matter – Leaves, dirt, and bacteria can cause green, brown, or black stains.
Chemical Imbalance – Incorrect pH, alkalinity, or sanitizer levels can lead to discoloration and scale formation.
Oils and Lotions – Sunscreen, body oils, and lotions can create a greasy residue that attracts dirt and stains.
Metal Contamination – Iron or copper in your water can lead to rust-colored or blue-green stains.

Step-by-Step Guide to Removing Stubborn Stains

1. Drain the Hot Tub

Before tackling tough stains, it’s best to drain your hot tub for easier access.

Turn off the power to the hot tub.
Attach a hose to the drain valve and let the water completely empty.
Rinse out any remaining debris with fresh water.

2. Identify the Type of Stain

Different stains require different cleaning methods:

White, chalky stains – Calcium buildup.
Green or brown stains – Organic matter or algae.
Rust-colored stains – Iron deposits.
Blue-green stains – Copper from water sources or corrosion.

3. Use the Right Cleaning Solutions

For Calcium and Hard Water Stains

Mix equal parts white vinegar and water.
Apply the solution to the stained areas with a soft sponge.
Let it sit for 10–15 minutes before scrubbing with a soft brush.
Rinse thoroughly with clean water.

For Algae and Organic Stains

Use a mild hot tub surface cleaner or diluted bleach solution (1 part bleach to 10 parts water).
Scrub the affected areas gently with a non-abrasive sponge.
Rinse well to remove any cleaner residue.

For Metal Stains (Iron or Copper)

Use a commercial stain and scale remover designed for hot tubs.
Follow the product’s instructions and allow it to break down the stain.
Scrub lightly and rinse.

For Oil and Grease Stains

Apply baking soda or a non-abrasive cleaner to the stains.
Scrub with a soft cloth or sponge in circular motions.
Wipe away the residue and rinse thoroughly.

4. Scrubbing and Rinsing

Use a soft-bristle brush or non-abrasive sponge to avoid damaging the shell.
Work in small sections to ensure even cleaning.
Rinse with fresh water after scrubbing each area.

5. Refill and Balance Water Chemistry

Refill your hot tub with clean, fresh water.
Test the water and adjust pH (7.2–7.8) and alkalinity (80–120 ppm) as needed.
Add sanitizer and other necessary chemicals to maintain clean water.

Preventing Stains in Your Hot Tub

Preventing stains is easier than removing them. Here are some simple steps to keep your hot tub looking clean:

1. Maintain Proper Water Chemistry

Test water weekly and adjust chemicals as needed.
Keep pH, alkalinity, and sanitizer levels balanced.

2. Use a Water Softener if Needed

If you have hard water, consider using a water softener or pre-filter when filling your hot tub.
This reduces calcium buildup and mineral stains.

3. Clean the Hot Tub Regularly

Wipe down the shell weekly to prevent buildup.
Use a skimmer net to remove leaves and debris.

4. Shower Before Entering

Rinse off oils, lotions, and sweat before using the hot tub.
This helps prevent oily residue and scum lines.

5. Use a Hot Tub Cover

Keep your hot tub covered when not in use.
This prevents debris, algae growth, and evaporation-related staining.

Keep Your Hot Tub Stain-Free

Regular maintenance and proper water care are key to keeping your hot tub shell clean and stain-free. By following these steps, you can easily remove stubborn stains and prevent new ones from forming, ensuring your hot tub remains a relaxing and inviting space. If stains persist despite your efforts, consider using specialized cleaning products or consulting a professional for deep cleaning services.