There’s nothing better than a refreshing dip in your backyard pool on a sweltering Aussie arvo. But what if you notice a thick layer of white foam or suds on the surface of the water, making it look more like a bubble bath than a sparkling sanctuary?

Pool foam can be a bit of a shock, but it’s a surprisingly common issue. It’s usually a sign that something is out of whack with your pool’s chemistry or cleanliness. While it might look harmless, it’s a symptom you shouldn’t ignore. Left untreated, it can lead to more serious problems like cloudy water, algae growth, and even damage to your pool equipment.

So, what causes pool foam? Let’s break down the most common culprits and, more importantly, how you can fix them and get your pool back to its beautiful best.

Organic Contaminants: The “Human Factor”

This is, by far, the most frequent cause of pool foam. Think about all the things people bring into the pool with them:

• Body Oils and Sweat: Even a quick swim without a pre-swim rinse leaves behind natural body oils.
• Hair and Skin Products: Shampoo, conditioner, hairspray, deodorant, and makeup all contain chemicals called surfactants. These are designed to create suds and foam, and they don’t magically disappear when you jump in.
• Sunscreens and Lotions: The waterproof properties of these products mean they sit on the surface of the water, and when agitated by a pump or swimmers, they can create a foamy layer.
• Detergents: Residue from washing powder or fabric softener left in swimmers’ cossies can easily be a foaming culprit.

Essentially, all these things act like soap in your pool water. When the water is agitated by the jets, swimmers, or a strong breeze, these organic compounds create a stable foam that doesn’t break down easily.

Chemical Imbalance: The Invisible Culprit

Your pool’s water chemistry is a delicate balance. When it’s thrown out of whack, a whole host of problems can arise, including foam. The key players to watch are:

• Low Calcium Hardness: If your pool water is too “soft” (meaning it has low calcium hardness), the surface tension of the water increases. This makes it easier for foam to form and less likely for it to dissipate. The ideal range for calcium hardness is between 200 and 400 ppm.
• High Total Dissolved Solids (TDS): TDS refers to all the inorganic and organic matter dissolved in your pool water, including everything from salts and minerals to the contaminants mentioned above. As TDS levels rise over time, the water becomes thicker, and foaming is a common side effect.
• Incorrect Algaecide Use: Some cheaper algaecides contain a type of chemical called quaternary ammonium compounds (quats). While they are effective at killing algae, they are also notorious for causing a thick, persistent foam. Always opt for a high-quality, non-foaming algaecide and follow the dosing instructions to a T. Overdosing can also be a major cause of suds.

Air in the System: The Mechanical Problem

If your pool water chemistry is perfect and you’ve been strict with a “shower before you swim” rule, the foam might be a sign of a mechanical issue. An air leak on the suction side of your pool’s plumbing can draw air into the system. This air is then blasted back into the pool through the return jets, creating a stream of fine bubbles that can lead to foam.

Check these common culprits for air leaks:

• Low Water Level: If your water level drops below the skimmer, the skimmer will start sucking in air instead of just water.
• Pump Lid O-Ring: The O-ring on your pump lid can crack, dry out, or become dislodged, allowing air to be drawn in.
• Loose Connections: Check the plumbing connections and fittings on the suction side for any loose parts.

How to Fix Pool Foam: A Step-by-Step Guide

Now that you know what causes the foam, here’s how to get rid of it and keep it from coming back.

Step 1. Test Your Water

This should be your first port of call. Grab a reliable test kit or take a water sample to your local pool shop for a professional analysis. Pay close attention to pH, total alkalinity, and especially calcium hardness and TDS levels.

Step 2. Shock the Pool

A good shock treatment is often the quickest and most effective way to address foam caused by organic contaminants. The high dose of chlorine will oxidise and break down the “soapy” compounds, getting rid of the foam and sanitising the water at the same time. Do this in the evening to maximise the chlorine’s effectiveness.

Step 3. Clean Your Filter

Foam-causing compounds can get trapped in your filter. Give your cartridge filter a good hose down or backwash your sand filter thoroughly to remove any gunk that could be contributing to the problem.

Step 4. Adjust Water Chemistry

If your water test reveals low calcium hardness or a pH imbalance, adjust it accordingly. Use a calcium hardness increaser to bring the levels into the correct range.

Step 5. Check for Air Leaks

If all else fails, it’s time to investigate your pool equipment. Ensure your water level is correct, check your pump lid and O-ring, and tighten any loose connections. If you can’t find the source of the leak, it might be time to call in a pool professional.

Step 6. Use a Defoamer

For an immediate, temporary fix (say, if you’ve got a barbie planned and need the pool looking schmick), you can add a pool defoamer. These products don’t solve the underlying problem, but they will break down the foam on the surface instantly.

How to Prevent the Pool Foam

The best way to deal with pool foam is to stop it before it starts.

Encourage Pre-Swim Rinsing: Gently remind everyone to have a quick shower before they jump in.

Use Quality Chemicals: Invest in good quality, non-foaming algaecides and other pool chemicals.

Regular Maintenance: Keep on top of your weekly water testing and cleaning routine to prevent the build-up of contaminants and keep your water perfectly balanced. Using a reliable pool cleaner can make this routine much easier and more effective.

Conclusion

Pool foam might be annoying, but it’s not a mystery. By understanding what causes it and taking a few simple steps, you can get your pool back to being the crystal-clear, inviting oasis you love. To make your life even easier, consider investing in the best pool cleaner to handle the daily grime and prevent the build-up of contaminants that often lead to foaming in the first place. With a little knowledge and a consistent routine, you can spend less time worrying about what’s on the surface and more time enjoying the water.