How to Prevent and Treat Hot Tub Algae

If you own a hot tub, you probably bought it because you wanted a nice, restful, and stress-free place to relax, gather with friends and family, and have fun. Nothing, however, ruins the hot tub experience faster than looking down and seeing a greenish tinge in the water. This, of course, is algae, and algae is a common issue for hot tub owners, especially in a warm, sunny place like Tucson.

Fortunately, it's possible to prevent hot tub algae from forming in the first place, and if it does, you can treat your hot tub or spa water to get rid of it and keep it under control.

Keep reading to learn how to prevent and treat hot tub algae and have a hot tub that you can be proud of.

What Causes Algae Growth in Hot Tub Water or Spa Water?

Algae are small, microscopic plants that thrive in warm, wet environments. While not really dangerous on their own, they can create unsanitary conditions, plus algae makes surfaces slick and make chemical balancing difficult. If left untreated, algae can clog up filters, damage equipment, and lead to bacteria growth.

The most common causes of algae growth include:

• Poor water circulation – Stagnant areas allow algae to multiply. Proper filtration is imperative.

• Imbalanced water chemistry – Low sanitizer or incorrect pH creates ideal growth conditions. A neglected spa is perfect for algae growth.

• Warm temperatures – Tucson’s hot weather can accelerate algae growth.

• Debris and contaminants – Organic material like leaves, dirt, and sweat feed algae.

• Direct sunlight – UV exposure encourages algae to bloom in uncovered spas. Sunlight makes algae flourish.

Signs of Algae in a Hot Tub

It might not be totally obvious when algae begins to grow in the hot tub. Some of the main signs include:

• Green, yellow, or black water discoloration, or surface fungi.

• Cloudy or murky water, or floating white slime.

• Slippery hot tub shell, walls, or steps

• Unusual moldy odor from the water

• Poor water clarity despite regular sanitizing

Recognizing these early signs makes algae easier to treat before it becomes a major issue.

Types of Algae Found in Hot Tubs

Not all algae are the same type of plant. Understanding the different types will help you determine which treatment option is the best.

Green Algae – The most common type, causing cloudy or green-tinted water. Usually floats freely or clings lightly to surfaces.

Yellow or Mustard Algae – Less common but more resistant to sanitizers. Often appears as yellowish patches on spa walls or steps.

Black Algae – Rare in hot tubs but very stubborn. Appears as black spots with deep roots that penetrate surfaces.

How to Prevent Hot Tub Algae - Preventing Algae Growth is the Best Way to Deal with It

The best way to deal with algae is to prevent it in the first place. An extreme contamination of algae is very difficult to deal with, but preventative care is very easy to do.

1. Maintain Proper Water Chemistry, Alkalinity Levels, and pH Levels

• Keep sanitization chemicals (chlorine or bromine) at recommended levels. A properly sanitized tub will be a good preventative against algae.

• Test water at least two to three times per week with test strips, and add chemicals to get the proper balance.

• Maintain pH between 7.2–7.8 for effective sanitizer performance. If there are not enough sanitization chemicals nor a balanced pH, this won't matter.

• Balance total alkalinity and calcium hardness to avoid instability. The hot tub's water chemistry is very important when trying to prevent algae. Hot Tub Chemical Balance must be taken into consideration.

2. Ensure Good Circulation

• Run the circulation pump daily to keep water moving. This keeps water contaminants in check.

• Clean filters regularly to prevent clogs. Don't let organic matter build up.

• Inspect jets to make sure water is circulating evenly. Jet nozzles can get clogged.

3. Use a Quality Hot Tub Cover

• Cover the spa when not in use to block debris and reduce UV exposure. Leaving the hot tub uncovered can quickly lead to algae and harmful bacteria growth.

• Ensure the cover fits securely to minimize heat and chemical loss. A cover that doesn't fit well, like a waterlogged hot tub cover, can become an algae magnet.

4. Shower Before Entering the Spa

• Encourage bathers to rinse off lotions, sweat, and oils before using the hot tub. These can make the water dirty.

• Reducing organic contaminants keeps water cleaner longer.

5. Schedule Regular Maintenance

• Shock the hot tub weekly to oxidize contaminants.

• Do regular ongoing maintenance to your hot tub. Spa maintenance is very important.

• Deep clean the spa every few months, including draining, scrubbing, and refilling. Use a gentle cleanser at other times when doing a thorough cleaning. Though its a time consuming process, it's an important one.

• Replace filters as recommended by the manufacturer.

How to Treat Algae in a Hot Tub

Even with the best prevention, algae can still develop. When that happens, swift treatment is key.

Step 1: Shock the Hot Tub

• Use a chlorine or non-chlorine shock treatment to kill algae spores.

• Follow the manufacturer’s instructions for dosage.

• Leave the cover off during shocking to allow gases to escape.

Step 2: Scrub Surfaces

• Use a soft brush or spa-approved scrubber to remove algae from walls, steps, and jets.

• Pay special attention to corners and crevices where algae can hide.

Step 3: Clean or Replace Filters

• Rinse filters thoroughly with a hose.

• Use a filter cleaner for stubborn algae or replace the filter if heavily contaminated.

Step 4: Balance Water Chemistry

• After shocking, retest the water.

• Adjust pH, alkalinity, and sanitizer levels to the correct range.

• Keeping water balanced helps prevent algae regrowth.

Step 5: Repeat If Necessary

• Stubborn algae (especially yellow or black varieties) may require multiple treatments.

• Consider using an algaecide approved for hot tubs if algae persists.

Long-Term Strategies to Keep Algae Away

Beyond regular cleaning and maintenance, hot tub owners in Tucson can take additional steps for long-term algae prevention:

• Install a UV or Ozone System – These systems help kill bacteria and algae, reducing reliance on chemicals.

• Schedule Seasonal Inspections – Hot tubs exposed to Tucson’s summer heat may need extra checks to ensure water quality.

• Drain and Refill Regularly – Fresh water every three to four months prevents buildup of contaminants.

• Work with Professionals – Partnering with a trusted pool and spa company ensures algae problems are treated quickly and effectively.

When to Call a Professional

While minor algae issues can often be resolved with DIY treatments, there are times when calling a professional is the best option. Homeowners should seek expert help if:

• Algae returns frequently despite proper care.

• Water chemistry is difficult to balance.

• Black algae or stubborn stains won’t go away.

• The spa equipment shows signs of clogging or damage.

For residents in Tucson, E-Konomy Pool Service & Supplies offers professional hot tub cleaning, maintenance, and repair. Their team can eliminate algae problems, restore proper water chemistry, and keep spas in peak condition year-round. They can also detail how to troubleshoot hot tub temperature problems.

Algae in a hot tub is more than just an eyesore—it creates unsafe, unsanitary conditions and can damage spa equipment if left untreated. By keeping water chemistry balanced, ensuring proper circulation, using a high-quality cover, and practicing regular cleaning, hot tub owners can prevent algae growth before it starts. Our team can also share insight on how to maintain a saltwater hot tub.

When algae does appear, shock treatments, scrubbing, and filter cleaning usually resolve the problem. For more intensive infestations, professional service ensures algae is eliminated at its source.

With proactive care and support from trusted experts like E-Konomy Pool Service & Supplies in Tucson, AZ, hot tubs can remain clean, safe, and ready to enjoy in every season.