Should I Use a Defoamer or Drain the Water?

Should I Use a Defoamer or Drain the Water?

Hot tub foam can show up out of nowhere, and it’s usually right when you’re ready to relax. One minute the water looks fine, the next it’s covered in white, sudsy bubbles that just won’t disappear. So what’s the right move, a quick defoamer or a full drain and refill?

What’s Actually Causing the Foam?

Foam doesn’t appear for no reason. It’s usually the result of contaminants building up over time, even if your water looks clean.

Common causes include:

  • Leftover shampoo, lotion, and body oils

  • Laundry detergent from swimsuits

  • Low sanitizer levels

  • High dissolved solids (TDS)

  • Dirty or clogged filters

When these mix with warm, circulating spa water, they create long-lasting bubbles that a defoamer can only hide temporarily.

When a Defoamer Is the Right Choice

A spa-safe defoamer works almost instantly, breaking down surface bubbles within a few seconds. It’s convenient, especially if foam appears unexpectedly during a soak.

Use a defoamer only when:

  • The foam is new and hasn’t happened before

  • Your water still smells clean

  • Your sanitizer and pH levels are balanced

  • You’ve recently cleaned or rinsed the filter

In these cases, a small dose is enough to clear the water so you can enjoy your hot tub without interruption.

(If you want a deeper clean later, adding a product like Spa Purge can help break down hidden organics in the plumbing.)

When You Should Drain and Refill Instead

If foam keeps coming back, it’s a sign your water is overloaded with contaminants that a defoamer can’t fix.

Consider draining your hot tub if:

  • Foam returns quickly after using defoamer

  • The water feels slippery or looks dull

  • There’s a musty or sour smell

  • You’ve had the same water for 3–4 months

  • Your total dissolved solids (TDS) are high

Fresh water instantly resets the spa. After a few months, even well-maintained hot tubs collect oils and residue that filters and chemicals simply cannot remove.

How to Prevent Foam in the Future

Keeping foam away is easier than fixing it after it shows up.

Try these tips:

  • Rinse filters every 1–2 weeks

  • Shower before soaking, especially after wearing lotions or makeup

  • Run a purge product every 3–4 months before draining

  • Wash swimsuits with water only, avoid detergent

  • Keep sanitizer levels steady to break down oils before they build up

A little routine care keeps your water clear, balanced, and foam-free longer.

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