Air Bubbles in Hot Tubs (Causes & How To Prevent It)

air bubbles in hot tub

When a hot tub user notices air bubbles, he or she should consider two possible causes:

  • Reduced water flow
  • Imbalanced levels of calcium hardness

Note: The use of surfactants will help reduce the surface tension of the water. This means that more bubbles will form and last longer.

The air bubbles will group together to form a foam. While the bubbles in a hot tub may not be noticeable at first, they will eventually group together to form a dense layer of foam.

Aside from the two possible causes of air bubbles in hot tub, there are other sources of this problem.

What causes air bubbles in a hot tub?

1. Imbalanced water levels

If you notice a lot of foam on your hot tub, then there may be a few causes of this problem. One of these is low calcium hardness.

The calcium in your hot tub is important for preventing excessive foaming, but if your tub is not hard enough, you should add a calcium hardness booster.

If the level is low, you can use a test kit to check the level of calcium and add a corrective agent to restore balance.

Another possible problem with high pH levels is brown scum. A pH decreaser can help reduce the pH level to a healthy 7.6. You can find a pH decreaser in the Buy Now link below. Another issue that can arise due to high pH is metals in the water.

The chemistry of your water must be balanced to prevent these issues. Metals and other contaminants are best removed from the water, but they aren’t totally removed.

If your hot tub has air bubbles, you should reduce the air bubbles. This will prevent water from evaporating into the air, which will lead to a lower pH level.

While you’re at it, you should also check the filters regularly to make sure they aren’t clogged with dirt or other debris.

Also, check the manufacturer’s recommendations to ensure your hot tub is equipped with the correct water chemistry.

If you’re experiencing an uncomfortable foamy water issue in your hot tub, it’s likely due to an overgrowth of the biofilm. You can remove this buildup by draining the water completely and refilling it again.

An anti-foam chemical can temporarily break the bond between water and surfactants, but the problem will return once the anti-foam is gone.

2. Lack of calcium hardness

If your spa is producing foam, it may be because the water has low calcium hardness levels. These bubbles are caused by impurities and soap residue that are left behind in the water. Some city-supplied water is “soft water” and isn’t hard enough to prevent foaming.

To prevent these bubbles, use a calcium hardness booster in the water.

Adding calcium to your spa water should be done regularly to avoid the appearance of foam in your tub.

If you suspect a problem, it’s important to know that calcium hardness is a fairly easy problem to resolve. Water tests can determine whether your tub has an excess of calcium, and if you need to add more calcium.

If you notice that the water is yellow, you may have a low calcium hardness level. If the problem persists, you can correct it by trucking in some fresh water and filling the hot tub with it.

If you don’t notice bubbles in your hot tub water, the most likely cause is low calcium hardness. Low calcium levels can decrease the surface tension of the water, causing air bubbles in hot tub water.

The calcium hardness level should be at least one percent higher than its normal level to prevent the problem. Low calcium hardness may be caused by improper pH levels or buildup of beauty products in the water.

One of the main reasons why air bubbles in hot tub water are caused by a lack of calcium hardness is due to an excess of lime in the water.

The amount of calcium in water depends on where you live and how hard your water is. If your hot tub is in the south, your water supply is likely to be hard and if you live in the north, it is likely to be soft. If you’re in the north, you might need a water softener.

3. Reduced water flow

If your hot tub isn’t producing enough water, you may have reduced water flow. This can be caused by several different causes.

For example, the water in your tub is too hard and may be allowing air to enter the system.

Another possible cause is a clogged or dirty filter. To fix this problem, you should clean or replace the filter. Other possible causes include a blockage in the water lines, a damaged pump, or a dirty filter.

If you suspect an air lock in your circulation pump, the hose used to fill your tub can be inserted into the filter opening. This will force air from the circulation system. If you can see air bubbles, then your circulation pump has a problem.

Depending on how the water is coming in and out, this can be a cause for your reduced water flow. If you suspect a hose or pump problem, it might be time to contact your manufacturer’s service department.

Another possible cause for reduced water flow is an air lock. In this case, the water will not circulate properly through the hot tub’s heater. If you see no bubbles at all, you’re probably experiencing an air lock.

This is caused by trapped air, which may restrict water flow through the heater and filter. If this happens, the water flow is greatly reduced. However, the good news is that most of these problems can be easily fixed.

If you have discovered reduced water flow due to air bubbles in your hot tub, the solution is to bleed the water.

To do this, open the air-bleed valve, usually located on the motor face. Then, tighten the air-bleed screw and replace the access panel. Alternatively, you can replace the access panel to the hot tub.

Once you have completed this, you will have a water-flowing hot tub once again.

Surfactants reduce the surface tension of water

The main function of surfactants in hot tubs is to break the surface tension of water, allowing the water to wet a surface more easily.

Every surfactant has two ends – the hydrophobic end and the water-fearing end.

This term derives from Greek roots, as oil and water do not mix. The hydrophobic end reduces the surface tension of water, making it easier for you to wet a textured surface.

To control the buildup of surfactants, make sure that you regularly change the water in your hot tub. Dissolved solids, including detergent residue, soapsuds, and even biofilms, can reduce the water’s surface tension. To reduce this buildup, you can use an “anti-foam” chemical. However, these chemicals only work for a day.

A surfactant can lower the surface tension of water in hot tubs by as much as 40 percent. However, this is not a solution for every hot tub. There is an optimal amount of surfactants per litre of water. Depending on the type and concentration of the surfactant, it can be as low as 0.025 g/L in hot tub water. The amount of surfactants in your hot tub water depends on how thick or thin your water is.

When a surfactant is in water, it organizes into a sphere shape and protects its ends from water. This micelle traps the hydrophobic soil beneath the surface. This is referred to as the Critical Micelle Concentration (CMC).

Using the correct chemicals to clean your hot tub

One way to make sure your hot tub is sanitized is by using the correct chemicals. Chlorine is an excellent sanitizer, but it doesn’t work well if the water is dirty. Bacteria and fungi can stick to the hot tub’s plumbing and prevent it from receiving the right amount of chlorine. The more they adhere, the less effective chlorine is, and the water will eventually become hazy or brown.

Adding the correct chemicals to your hot tub is easy if you follow these simple tips. To begin with, test the amount of chlorine and bromine in your tub.

The ideal levels are between one and three parts per million, or 1 to 3 ppm of each.

Make sure to test the pH level of your hot tub as well, and add chemicals as necessary. For best results, you should test the chemicals daily, or every few days, depending on your usage.

If you have a spa, it’s also important to use a sanitiser. A hot tub’s water contains bacteria that can multiply very quickly.

To prevent these bacteria from thriving, you’ll want to use a sanitiser to kill them. Chlorine tablets and granules are the most effective and economical sanitisers. If you’re unsure, you can also try bromine or chlorine tablets.


The chemicals used to clean your hot tub depend on whether you want a fresh-looking spa or one that’s heavily stained.

To avoid a swampy spa, use a surface cleaner or an all-purpose cleaning product.

Be sure to check the manufacturer’s instructions before using a household cleaning product, as regular household cleaners may be too acidic and can damage the shell of your hot tub.

Afterwards, use the same process to clean the cover of your hot tub.