Can You Put Pool Chemicals in a Hot Tub

For those who own both a swimming pool and a hot tub, you may have looked at the stack of chemicals you have for each unit and noticed that they’re basically the same ingredients. You’ve probably asked yourself, “Can you put pool chemicals in a hot tub?” And although it’s a reasonable question, the fact is that you should never mix up your hot tub and swimming pool chemicals. Although they may have similar names on the containers, the concentrations of these chemicals are radically different.

Because of these different chemical concentrations, adding pool chemicals to your hot tub can drastically affect the pH levels, total alkalinity and chlorine levels which may make the water hazardous to bathe in. And if these levels get too far out of balance you can risk damaging your hot tub. So don’t be tempted to mix and match the next time you’re running low on a certain additive. In this article, we’ll explain the differences between swimming pools and hot tubs that make substituting chemicals a bad idea.


It doesn’t take an expert to notice that the temperature in a hot tub is much warmer than that of a swimming pool. Most hot tubs run as high as 40 degrees Celsius, whereas the average pool may get as high as 25 or 26 degrees Celsius. The higher temperatures found in hot tubs can cause chemical reactions to happen much faster and with greater vigour. Since swimming pool chemicals are already manufactured with higher concentrations than hot tub chemicals, using them at high temperatures can cause the pH and other levels to change drastically.


The fact that swimming pools hold so much more water than hot tubs is another reason that swimming pool chemicals are produced at much higher concentrations than hot tub chemicals. Keeping levels balanced in a hot tub requires lower concentrations and quantities of chemicals than those used for a swimming pool. For this reason, it’s inadvisable to try and substitute swimming pool chemicals for those made for a hot tub.

Water Jets

Both swimming pools and hot tubs have water jets, but hot tubs have many more jets per square foot than a swimming pool. And those jets circulate the water much faster and more effectively than the ones found in a swimming pool. For this reason, any chemicals added to a hot tub are mixed into the water much faster than those added to a swimming pool. And if you’re adding highly concentrated swimming pool chemicals into a hot tub, the rapid circulation could cause the water to become quickly and irrevocably unbalanced.


Because of the larger capacity of a swimming pool and the nature of how it’s used, swimming pools typically see many more users going in and out of the water. Because hot tubs see less activity, there is a propensity for the water to be more susceptible to radical changes in chemical levels. This is even more pronounced if the additives used are highly concentrated such as with swimming pool chemicals.


A combination of the heat of the water and the force of the water jets cause hot tubs to lose water to evaporation more quickly than a swimming pool. This evaporation increases the concentration of chemicals in hot tub water. Highly concentrated swimming pool chemicals can quickly become overpowering when used in a hot tub.


Soda ash is used to raise the pH and alkalinity in a swimming pool or hot tub. Using soda ash designed for swimming pools in a hot tub can cause the pH to rise to levels that are unable to be balanced without emptying and refilling the tub with fresh water.


Swimming pool chlorine tablets are quite acidic and can quickly wreak havoc on the pH levels of a hot tub. The hot tub’s total alkalinity buffering capacity is limited to the point of a massive drop in pH.

Now that you know about proper hot tub chemical usage, download a hot tub buyer’s guide below to find out more about our models, or visit us at our London hot tub store.

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