Foam in Hot Tub Water – Causes, Solutions, & Prevention

If your hot tub water looks like you just poured in a big bottle of bubble bath, it’s not a good sign. As a hot tub owner, you probably know that adding soap and suds can cause a foam problem and is hard on your spa equipment. So it’s doubtful you’ve added any of these taboos to your spa.

Unfortunately, foam in your hot tub water can result from several other causes.  The most probable causes of your foamy hot tub water are:

  • Low alkalinity
  • Soft water
  • Dirty filters
  • Detergents from swimsuits, hair products, and filter cleaners

Understanding each of these reasons and the solutions to each can help you resolve your current foamy hot tub water problem and prevent it from reoccurring.

Foam in hot tub cause #1

Low alkalinity is one cause of foamy hot tub water and is an easy fix. Just balance the alkalinity of your hot tub water to 80-150 ppm. This will serve as a spa deformer when low alkalinity is the cause of foam in your hot tub. To prevent low alkalinity from causing foam in the future, monitor the alkalinity level, and maintain it above 80 ppm.

Foamy hot tub water cause #2

Soft water can also cause foam in your hot tub. The simple solution to this problem is to increase your water hardness to 250 ppm. Just add a calcium increaser, and the calcium chloride in it will increase your water’s hardness and serve as a hot tub defoamer.

Foam in hot tub cause #3

Another cause of foamy hot tub water is dirty filters. If you haven’t been following a good maintenance regimen, there’s a strong probability your filters need a good cleaning. Even if you religiously adhere to a maintenance schedule, various factors can cause the filters to get dirty sooner. For example, maybe you left your hot tub uncovered, and debris got in it. Also, if your spa has had more use than usual, or if a bather went in wearing lotion or other contaminants, the filters might have gotten mucked up.

To clean your filters properly, follow these steps:

  • Soak your filters in a spa filter cleaner, such as Spa Marvel Filter Cleaner.
  • Remove all debris from the filters, including any debris in the filter pleats.
  • Thoroughly rinse the filters, preferably with a pressure washer. This helps ensure all debris is completely removed. If you don’t have a pressure washer, head to a coin-operated car wash to spray them. Then reinstall the filters.
  • Shock the hot tub water according to directions on the shock’s package, then wait at least 24 hours.
  • If foamy hot tub water persists, rinse the filters again with fresh water. Shock the water again, and wait another 24 hours.
  • Repeat this process until foam in the hot tub water is resolved.

Foamy hot tub water cause #4

As mentioned above, detergents and foreign matter can muck up your filters and wreak havoc, resulting in foam in the hot tub. Even after you’ve cleaned the filters, these troublesome contaminants can remain in the water producing foamy hot tub water. Some of the contaminants that can cause foamy hot tub water include:

  • Residual laundry detergent in bathing suits
  • Soap or shampoo residue on body or hair
  • Body lotions
  • Hair products
  • Spa fragrances
  • Filter cleaning agents if filters aren’t thoroughly rinsed (Spa Marvel Hot Tub Filter Cleaner is the exception)
  • Low-quality hot tub water treatment products

To quickly but temporarily resolve the foam in hot tub water, use a hot tub defoamer. You can find a spa defoamer at your professional spa retailer.

Ultimately, however, you’ll probably want to use a hot tub defoamer method that will eliminate the foamy hot tub water permanently. So follow these steps as a permanent solution.

  • Shock the water according to package instructions, then wait at least 24 hours.
  • If there’s still foam in the hot tub, rinse the filters thoroughly with fresh water, shock the spa again, and wait 24 more hours.
  • Repeat step two as many times as needed to rid your spa of foam.
  • Also, consider adding a spa water conditioning product such as Spa Marvel Water Treatment & Conditioner. This can help to reduce and eliminate detergent-based foaming while decreasing the amount of chemicals needed to maintain your spa water.

Finally, there is a faster and easier permanent spa defoamer solution. Just drain and refill your hot tub to enjoy a fresh, foam-free start. This method is cheaper, too!

The cost of water, with the wastewater charge, is typically about 1.5 cents per gallon in North America. So a 400-gallon spa costs only about $6 to fill. The electricity to heat up the spa water with a 5 kW heater will raise 400 gallons of water by 7 degrees F per hour. So to raise the water temperature from 50 degrees to 100 degrees, it will take about 7 hours or 35 kW of energy. Energy costs vary from region to region. So in some areas, it will cost $2.80 for electricity to heat the water. In other jurisdictions, it will cost $6.65. In the end, your total cost is at most just under $10 to refill and heat a foamy spa.

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How to Shock a Hot Tub

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Why does my hot tub smell like chemicals?

Why does my hot tub smell like chemicals?

Chlorine breaks things down and becomes depleted doing so. When chlorine is depleted, it doesn’t just vanish, rather, it is converted to something called a chloramine (sometimes referred to as ‘combined chlorine’). All a chloramine does is give off that odour that people refer to as the chlorine odour.