How To Stop Algae In Spa Pools

Algae can take various forms from green, yellow, reddish to black. They can cause your water to take on a green tinge, become cloudy or feel slimy. Read on to find out what causes algae and how to get rid of it.

How To Stop Algae In Spa Pools hero

What do algae look like in a spa?

Algae can take various forms and colours from green, yellow, pink, white and even black. They can cause your water to take on a green tinge, become cloudy or feel slimy. If left for a prolonged period of time, they can form green or black slime.

The first indication of an algae bloom will be a significant increase in sanitiser use. You’ll find that you’ll be adding more and more sanitiser and still struggling to keep your water clear.

Algae are not bad characters in small doses however some can be toxic and no one really likes to share their spa with algae, which at the least, significantly reduces water clarity.

In this article, we'll discuss how to prevent algae and how to treat it if it rears it's ugly head in your spa!

How do I prevent algae in my spa?

Keep your spa covered when you’re not using it. This prevents things like dirt, pollen and bacteria from getting into your spa water. These things can all help feed algae in your water, so keep them out as much as possible! Shower before entering the spa to remove oils, lotions and dirt from your body. Make sure you are adding enough sanitiser for the water volume of your spa. The APVMA recommendation is 6-10g per 1000L every day for chlorine. Ensure you follow the directions on the back of your sanitiser label. Check and clean your filters and replace them when they are worn. Wash any swimsuits that have been used in other water sources (like lakes, rivers, pools or the sea).

Back to top

How do I get rid of algae in a spa?

If your water has been green for less than 24 hours then you may be able to bring it back around again. Follow the steps below;

  • Remove your pillows and use 60g of your sanitiser per 1,500l of water.
  • Leave the spa cover off for at least 20minutes and put the jets on for one cycle.
  • Leave the spa for a few hours, if this has worked you will see the water begin to clear within 12 hours.
  • Once clear and the sanitiser has dropped to a safe level, Balance the pH and alkalinity.

Once your water is balanced again you can continue to using your spa normally. If these steps don't work and your spa water still has a green tinge, you can try these more involved techniques below;

1. Use a spa shock to reduce algae

Spa shock can be used to help reduce algae however the effects are very short-lived, as these products are not true algaecides. Make sure you remove spa pillows, headrests and your cover before using spa shock.

2. Use a spa maintenance product

Poppit Pool & Spa Complete Maintenance followed by frequent cleaning of your spa filter cartridges with Poppit (phosphate-free) Filter Cartridge Cleaner will not only remove the problem, but it is also extremely effective prevention.

3. Use an algaecide to remove algae in spa water

Poppits® 3 month algaecide is considered to be the strongest. This is the only algaecide compatible with chlorine-free (Hydrogen Peroxide) sanitiser.

Follow instructions on the label of the algaecide. 30 mL / 1,000 litres is generally sufficient to kill the algae and will clean up the spa within 48 -72 hours. This will provide protection for the life of the water in the spa. NOTE: (Phosphate removers do not actually remove phosphates from your spa. Instead, they form an insoluble molecule that becomes trapped in the filter. This means it is important to regularly clean your spa filters, especially after using an algaecide

Back to top

4. Soak and clean your filter cartridges

Make sure to soak and clean your filter after using these algaecide and phosphate-removing products.

We recommend the Poppit spa filter cleaning solution because it is the only filter cartridge cleaner that can make the claim that it is free of phosphate, sulfate or nitrate. All of which act as Hors d’oeuvres at the algae party.

Use a filter cleaning wand to rinse your filters thoroughly.

5. Empty your spa water

If an algaecide is not completely effective within 72 hours and there are still signs of algae, you will need to empty your spa water and replace it with fresh water. You'll need to re-balance and sanitise your spa. Follow the directions in the water quick start up guide if you need help.

6. Replace your Filter cartridges regularly

Ensure you are replacing your filter cartridges regularly. We recommend replacing your filters every 11-12 months for a standard spa with normal use and every 12-18 months for a swim spa. Spas with higher usage may require the filters to be replaced more regularly.

Back to top

Is green spa water safe?

Green water in your spa is most likely caused by algae growth that has been able to thrive because of insufficient sanitiser. This could mean your water is not safe to enter as there will likely be bacteria and other microorganisms that have been able to multiply in your spa water.

Can algae in a hot tub or spa make you sick?

Some forms of algae are harmful to your health. Algae in your spa water is also a sign that something is not right with your water balance. Algae will form when your sanitiser is not working properly, which can mean that other invisible bacteria may have formed in your spa water.

What causes algae in a hot tub or spa pool?

Algae is a tiny plant-like microorganism that grows in water. Like all organisms, it needs food to grow. The main source of food for algae is phosphate - which is a naturally occurring inorganic chemical that is widely used in detergents, animal feed and fertilizers.

Many common household laundry detergents, soaps, shampoos and beauty products contain phosphates. When you and your guests use your spa, small amounts of residual phosphates will remain in your spa water - leaving food for algae!

Other contributing factors to algae growth include;

  • Algae can form when the water pH is not between 7.2 and 7.8
  • Not enough sanitising product is being used, or not often enough
  • Leaving your spa water exposed to the sunlight with the cover off can create an environment where algae will grow.
  • Your filters aren’t being cleaned regularly
  • Your filters need replacing

Have algae crashed your spa pool party?

Got more questions?

Talk to us on live chat, or email us your spa questions and we'll be happy to help!

Back to top

Five Star Trust Pilot Rating

We are proud that Spa World customers have given us a Five Star Trustpilot rating.