Spa foam is almost always a water quality issue, not an equipment one. Here is what is causing it and what to do about it.
What Causes Spa Foam?
Foam forms when Total Dissolved Solids (TDS) accumulate in the water to the point where they start clinging to air bubbles produced by the jets. The result is the layer of foam you see on the surface.
TDS builds up from a combination of sources — some obvious, some less so:
Body products
Lotions, sunscreen, deodorant, hair spray and soap residue from unwashed swimwear
Sweat and skin cells
Every person who uses the spa adds perspiration and dead skin cells to the water
Treatment chemicals
Sanitisers, balancers and other water treatment products all contribute to TDS over time
Most of these particles are too small to be filtered out. They simply dissolve into the water and accumulate with every use.
Why Does It Get Worse Over Time?
Foam is the first sign that TDS levels are getting too high. If nothing changes, the water will eventually reach full saturation — permanently cloudy water that no amount of filtering or chemical treatment will restore. At that point, draining and refilling is the only option. Getting ahead of it is far easier than dealing with it once it has gone that far.
What to Do About It
Right now
If you need to use the spa today, an anti-foam product like Aquaspa Anti-Foam will knock the foam back quickly. It does not fix the underlying issue, but it buys you time and keeps the spa usable while you address the water quality properly.
Longer term
The only genuine fix is a water change. Aim to drain and refill your spa every 8 weeks under normal use. You can extend that window by:
Shower before getting in
Rinsing off body products and sweat before entering the spa makes a significant difference to how quickly TDS builds up.
Rinse your swimwear without detergent
Detergent residue in swimwear is one of the fastest ways to generate foam. Rinse only, no soap.
Test your water regularly
Keeping sanitiser and pH levels in range slows TDS accumulation and catches problems before they become visible.
