Can Epsom Salt Be Used In A Hot Tub?


No, you cannot use Epsom salt in a hot tub! In addition to corroding your hot tub’s plumbing, Epsom salts can also cause flash burns when you add them to brominated or chlorinated water present in a hot tub.

Epsom salt and hot tubs are popular for their easing of pain for both joints and muscles. For this reason, many people resort to using Epsom salt in their hot tubs.

Nonetheless, using this compound isn’t recommended in a hot tub. In this primer, we shall learn why using Epsom salt in a hot tub isn’t recommended. We shall also look at a scenario when using Epsom salt in a hot tub is safe.

Why You Shouldn’t Use Epsom Salt In A Hot Tub

You should not use Epsom salt inside a hot tub because of the following reasons:

Raises The Number of Dissolved Solids

Many people use Epsom salt commonly in bathtubs. When used in a normal bathtub, the recommended addition is only two cups for full therapeutic effects.

Averagely, bathtubs can accommodate roughly 80 gallons of water. On the other hand, a normal hot tub can hold approximately 400 – 500 gallons of water. In order to attain a similar absorption inside your tub, you’ll have to add 10 to 12 Epsom salt cups.

This is quite huge.

Draining bathtubs is easy. You can drain your regularly. This isn’t the case with hot tubs.

In order to prevent the accumulation of scale in your hot tub’s equipment and surfaces, experts recommend draining your tub once its total dissolved solid levels get to 1,500 ppm. If you fail to do this, you can void its warranty.

By adding 10 – 12 cups of Epsom salt into your bathtub, you can effortlessly raise the number of dissolved solids surpassing the maximum threshold of 1,500 ppm. While hot tub heaters can sustain damage from the accumulation of scale, the unit’s water lines, tub surfaces, pool pumps, and jets can experience scale buildup if an optimum water balance isn’t maintained.

Harsh Chemical Reactions

Epsom salt, in its pure form, also goes by the name magnesium sulfate. As a compound, it brings with it mildly acidic properties, that disrupts your hot tub’s water pH balance. Unbalanced levels cause other issues including:

  • Ineffective performance of the sanitizer
  • Rusting of important hot tub elements (metal parts, plastic pieces, seals, and gaskets)

Chlorine is the most commonly used chemical in hot tubs. Magnesium and chlorine shouldn’t mix. Their reaction can result to flash burns.

Adding Epsom salt into a hot tub with chlorine puts users at risk of serious injuries especially burns.

Is Epsom Salt Also Harmful to an Inflatable Hot Tub?

Just like with normal hot tubs, Epsom salt can also damage the inflatable tub. You should avoid using them in such a tub as well.

Although inflatable hot tubs lack the sophisticated PVC pipe system that is common with the conventional ones, they still feature plumbing elements such as the heater.

On top of that, you are also at the risk of mixing the compound with water laded with bromine/chlorine. Some people are dead set on using the compound on their inflatable hot tub. If you are one of them, it is important to note that you should only do so if the water content is fresh. In this case, you should follow the steps we have outlined in the next section.

The good thing about inflatable hot tubs is the fact that they are more portable compared to the traditional ones.

When Can You Safely Use Epsom Salt In A Hot Tub

Having established that Epsom salt is dangerous when used in a hot tub, let us now look at when it is safe to use it.

Chlorine and bromine are dangerous when mixed with Epsom salt. If the water in your hot tub does not have chlorine and bromine, then you can safely add Epsom salt.

For you to add Epsom salt in your hot tub, the first thing you need to do is drain the chemical-filled water. Once you do that, fill the tub with fresh water. Add just some little amount of Epsom salt into the freshwater (avoid adding too much).

After you are through with the salt session, it is necessary to drain all the water out. Afterward, thoroughly clean and flush the tub in order to prevent the corrosion of important elements of your tub.

The rule of thumb with a hot tub is to make sure that you have an optimum balance of chemicals in the water.

Are Bath Bombs or Essential Oils Also Harmful to a Hot Tub Like Epsom Salts?

Unfortunately, yes! You should avoid using bath bombs or essential oils inside your hot tub.

The thing is, the design and build of hot tubs are such that they cannot circulate and/or screen thick items such as bath bombs or essential oils. Using oils not tailored for hot tubs might not only cause accumulation of scale but can also damage your hot tub over time.

What’s more, some oils cause photosensitive reactions to the skin. Bath bombs also leave oil behind that can damage the pipes if not cleaned thoroughly.

Another reason that makes bath bombs inappropriate for hot tub use is the fact that they come filled with flower petals, confetti, or glitter. Although they can make your tub look cool, they are notorious for damaging your tub’s jets. The particles clog up jets making them malfunction or in severe cases stop working.

If you still want to use bath bombs, you can put them inside a nylon sock first and then place it on water.

Alternatives To Epsom Salt In A Hot Tub

An effective alternative to Epsom salt in a tub is the use of elixirs. On top of helping you relax and moisturizing your skin, these are also efficient at softening water.

You can also use bath bombs specially tailored for hot tubs. Unlike the normal bath bombs, these do not clog your hot tub’s filters. Additionally, they do not alter water chemistry.

Editorial Staff

I'm Adnan Sabanovic, the guy behind Hot Tubs Report. I've had a chance to enjoy hot tubs last few years and have really become interested in owning one of them. Nearly every weekend you'll find me spending time with my family or playing sports. If I am not doing that then I'm here writing about tubs on Hot Tubs Report. This blog is a research for my first hot tub which I decided to document and share publically so others can benefit from it as well.

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