How Do I Remove Foam from My Hot Tub?

Use a foam reducer product to break down existing foam. Long-term prevention involves maintaining proper water chemistry and encouraging bathers to shower before entering the tub.

What Causes Foam in a Hot Tub?

Foam in hot tubs typically comes from substances that reduce water surface tension. When water is agitated, as it is with jets, these substances create bubbles that form foam.

Common foam-causing contaminants:

• Body oils and sweat

• Lotions, deodorants, and sunscreen

• Detergents and fabric softeners on swimsuits

• Hair products and makeup

• Low-quality or old spa chemicals

• Organic debris and scum buildup

• High total dissolved solids (TDS)

When these contaminants collect in the water, especially in hot, aerated conditions, foam forms and lingers.

Step-by-Step: How to Remove Hot Tub Foam

Step 1: Scoop Out Excess Foam

Start with the basics. Use a skimmer net or your hands to remove visible foam from the surface. This will not solve the underlying issue, but it can improve water clarity temporarily and prevent buildup in your filter.

Step 2: Use an Anti-Foam Product

Anti-foam (also called defoamer) is a fast-acting solution that collapses foam instantly.

• Shake the bottle before use

• Add the recommended dose with the jets running

• Wait a few minutes and observe the foam break down

Note: This is a short-term fix. Anti-foam does not remove contaminants. It simply suppresses the foam.

Step 3: Test and Balance Your Water

Foam often forms when water chemistry is off balance. Use test strips or a liquid test kit to check:

• pH

• Alkalinity

• Calcium hardness

• Sanitizer levels (chlorine, bromine, or salt)

Ideal ranges:

• pH: 7.4 to 7.6

• Alkalinity: 80 to 120 ppm

• Calcium hardness: 150 to 250 ppm

• Chlorine: 1 to 3 ppm or Bromine: 3 to 5 ppm

Low calcium levels, in particular, can cause soft water that foams easily.

Step 4: Shock the Water

Shocking your hot tub helps break down organic waste and oxidizes contaminants.

• Use a chlorine or non-chlorine shock, depending on your sanitizer

• Follow package directions for dosage

• Run the jets and leave the cover open for at least 30 minutes

Shocking removes unseen buildup and reduces total dissolved solids.

Step 5: Clean or Replace the Filter

Dirty filters trap oils, scum, and contaminants that can feed foam.

• Rinse the filter thoroughly with a hose

• Use a filter cleaner spray for deeper cleaning

• Replace your filter every 12 to 18 months, depending on usage

A clean filter is essential to keeping foam-causing particles out of the water.

Step 6: Drain and Refill (If Needed)

If foam returns quickly or the water smells off, it may be time to start fresh.

• Turn off the power to the spa

• Drain water completely

• Clean the shell with a non-abrasive spa surface cleaner

• Rinse thoroughly to remove residue

• Refill with fresh water and balance the chemistry

Water should be changed every 3 to 4 months, or more often with heavy use.

Preventing Foam in the Future

Once you’ve removed the foam, prevent it from returning by adopting good maintenance habits.

1. Rinse Before You Soak

Encourage anyone using the spa to rinse off in the shower first. This reduces:

• Lotions

• Sweat

• Hair products

• Skin oils

Clean skin means fewer contaminants entering the water.

2. Use a Swimsuit Just for the Hot Tub

Laundry detergents and softeners stick to fabric and rinse into your spa water.

Tips:

• Rinse swimsuits thoroughly before wearing

• Avoid using dryer sheets or fabric softener

• Designate hot tub-only swimwear

3. Maintain a Consistent Water Care Routine

Stay on top of your water chemistry:

• Test the water 2 to 3 times per week

• Clean the filter monthly

• Shock weekly or after heavy use

• Maintain proper sanitizer levels

Consistent upkeep helps prevent foamy conditions from forming.

4. Limit Spa Additives

Be cautious with products like bath oils, aromatherapy crystals, or bubble baths. Even spa-safe versions can increase the risk of foaming if overused.

If you do use them:

• Choose high-quality products designed for hot tubs

• Use the smallest recommended dose

• Test and adjust water chemistry afterward

5. Monitor TDS Levels

Over time, your water absorbs everything from bathers, air, and spa chemicals. This creates high TDS levels, which makes foam more likely.

• If TDS is too high, draining and refilling is the only reliable fix

• You can test TDS using a digital meter or have it checked at a spa store

Signs You’re Dealing with More than Just Foam

Sometimes foam is a symptom of a deeper issue. Keep an eye out for:

• Cloudy or discolored water

• A strong chemical or sour smell

• Slippery or slimy surfaces

• Irritated eyes or skin after use

If you notice these along with foaming, consider a full water change, deeper cleaning, and possibly professional testing.