Can You Put Pool Chemicals in a Hot Tub?

Have you ever found yourself in a situation where you’re running low on hot tub chemicals?  Taking a look around your stock you might’ve noticed that you had more than enough swimming pool chemicals to last the entire season, which made you wonder, “Can you put pool chemicals in a hot tub?”  At first glance, the chemicals appear very much the same.  But the fact is that swimming pool chemicals are much more concentrated than hot tub chemicals.  Substituting them could leave you with water that’s dangerous to bathe in or hot tub components that have become damaged.  In this article, we’ll go over some of the reasons why swimming pool and hot tub chemicals aren’t easily substituted for one another.

Differences in Water Volume

A swimming pool obviously has much more water than what’s found in a hot tub.  This is part of the reason why swimming pool chemicals are manufactured in a more concentrated form.  These high concentrations are diluted by the large volume of water in a swimming pool in a way that they can’t be in a hot tub.  Using swimming pool chemicals in a hot tub can cause extremes in pH, total alkalinity and chlorine levels which might not be easily regulated. 

Differences in Water Temperature

It’s also quite apparent that the water in a hot tub is much higher than that found in a swimming pool.  While most people run their swimming pools at around 80 degrees Fahrenheit, hot tubs can reach temperatures as high as 104 degrees Fahrenheit.  The increased temperature found in hot tubs can speed up chemical reactions and cause them to be much more thorough.  Combined with the higher concentrations found in swimming pool chemicals you can find yourself with rapid fluctuations and hard to control results. 

Differences in Water Circulation

Hot tubs typically have a large number of relatively powerful water jets concentrated in a small area.  Swimming pools, on the other hand, have a few jets affecting a much larger volume of water.  The agitation caused by hot tub jets ensures chemicals get mixed in with the water much faster than what happens in a swimming pool.  For this reason, swimming pools require larger quantities of more concentrated chemicals compared with hot tubs.

Differences in Capacity

Swimming pools are usually used for longer periods of time by more people who enter and leave the water more frequently.  The smaller number of people and lower levels of activity in a hot tub mean that chemical levels are more prone to fluctuations if they aren’t added in the right amounts or concentrations.  Using swimming pool chemicals in a hot tub will only exacerbate this problem.

Differences in Evaporation

Water evaporation is a problem in both swimming pools and hot tubs.  But because hot tubs run at higher temperatures and the water experiences much more churn, hot tub water evaporates more quickly than that found in a swimming pool.  Hot tub chemicals are specifically designed to account for this evaporation.  Swimming pool chemicals, on the other hand, are far too concentrated for a hot tub and can cause skin irritation and equipment malfunction when used improperly.

Differences in Chemical Concentrations

Like most of the points in this article show, swimming pool chemicals are manufactured in much higher concentrations than those made for hot tubs.  For example, swimming pool chlorine tablets are far too acidic to be used in a hot tub.  This can affect the buffering capacity of the total alkalinity and allow the pH to drop far too low.  Alternately, soda ash manufactured for swimming pool use can cause the pH of hot tub water to rise so high that the only way to rectify the situation is to empty the tub and refill it with fresh water.

Now that you know about using hot tub chemicals, download a hot tub buyer’s guide to learn more about routine maintenance.