How to Shock a Salt Water Hot Tub

By Calvin | Last Updated: June 23, 2021 | Maintenance / Water Chemistry

So, you want to shock your salt water hot tub but you don’t know how to go about it. Don’t sweat it. This post is going to explain the step-by-step procedure on how to shock your salt water hot tub.

You will also learn why you need to shock the salt water hot tub and the best type of shock to use. So if you are ready, let’s get on with it.

Shocking a regular hot tub is one thing, but shocking a salt water hot tub is another thing. Since salt water hot tubs have a chlorinator the shocking process can be different. So, how to shock a salt water hot tub? Find out with our 10-step guide.

Do You Need to Shock a Salt Water Hot Tub?

Yes, you need to shock a salt water hot tub. While it’s true that you don’t need to add sanitizers to a salt water hot tub, you do need to shock the hot tub regularly.

This question causes a lot of confusion since most hot tub owners believe having a salt water hot tub means they don’t have to worry about adding sanitizers to the water or even shocking the salt water hot tub.

Why Should You Shock a Salt Water Hot Tub?

To Kill Algae

The chlorinator in your salt water hot tub will keep the water clean but it wouldn’t prevent algae growth in the salt water.

The steady and slow chlorine production in the water by the chlorinator makes the hot tub vulnerable to algae attack. So, you need to shock the salt water hot tub regularly to kill the algae in the water.

To Increase the Lifespan of the Chlorinator

Asides from the algae attack, running the chlorinator in your salt water hot tub constantly is a bad idea. Yes, salt water hot tubs have a lot of benefits but there is also a downside.

Running the chlorinator constantly means it is at risk of wearing down faster and getting damaged. So give the chlorinator a break once in a while by shocking the hot tub.

Related Read >>> How to Convert To a Salt Water Hot Tub?

To Increase the Calcium Hardness of the Water

The chlorine produced by the chlorinator causes the water in the hot tub to get softer since salt is a natural remedy to hard water. While soft water is gentle on your skin, eyes, and hair, it’s not the same on your hot tub.

Soft water is usually under-saturated which means the water doesn’t have enough calcium. So, the soft water will gradually eat away at the metal parts of your hot tub like the jets and shell.

The more chlorine the chlorinator adds to the water, the softer the water will get and the more damage it can cause to the metal parts of your hot tub.

Shocking the hot tub will gradually increase the calcium hardness of the water so the hot tub isn’t at much risk of corrosion and discoloration.

So, now you know why you need to shock your salt water hot tub, but what type of shock is the best to use? Let’s take a closer look.

Related Read >>> Is Soft Water Bad For Hot Tubs?

What Type of Shock Is Best for Salt Water Hot Tubs?

The best type of shock to use for a salt water hot tub is chlorine shock. This shouldn’t come as a surprise since a salt water hot tub is still practically a chlorine hot tub.

The salt water hot tub still uses chlorine to clean the water. The only difference from a regular chlorine hot tub is that you don’t have to add the chlorine directly to the hot tub water by yourself. The chlorinator takes care of that.

The chlorine shock is heavily concentrated. The shock has a very high amount of chlorine sanitizer. It spikes up the chlorine faster and it is ideal for killing algae, bacteria, and other sorts of germs in the salt water pool. The chlorine shock will also get rid of chloramines in the water.

So how do you shock a salt water hot tub with chlorine shock? The answer to that is below but before that, let’s check out the tools needed to shock a salt water hot tub.

Tools Needed to Shock a Salt Water Hot Tub

Get your tools ready and let’s get on with the task.

Related Read >>> Can I Shock My Hot Tub After Re-Filling?

How to Shock Your Salt Water Hot Tub

Shocking your salt water hot tub isn’t difficult but it can be time-consuming so this isn’t a task to take on in a rush.

Put on Your Safety Gear

The first thing to do is to put on your safety gear. Your pair of gloves, breathing mask, and pair of goggles should be on you. Ensure these safety gears are fit for the task.

You will be handling some very active and acidic chemicals while shocking your hot tub. These chemicals shouldn’t come in contact with your skin and they shouldn’t be inhaled as well.

Take Out the Salt Cell Chlorinator

The chlorinator in your hot tub should be turned off. You should also remove it from the water before you go ahead with the task.

Test the Water

The next thing to do is to test the water in your hot tub. This is a very crucial step not just for shocking the hot tub but for every task that involves adding chemicals or sanitizers to the water. You need to know the chemical properties in the water before you shock the salt water hot tub.

Test the water and see the results. You need to check out your pH levels, chlorine, and bromine levels.

Use your water testing kit to check the hot tub’s pH level, calcium hardness, and chlorine level. It’s important to know all of these because adding a high dose of chlorine shock to a salt water hot tub with unbalanced water chemistry can lead to corrosion, staining, and even scale build-up.

After you have tested the chemical properties of the water, you should adjust them if they are off.

All of these levels should be right in your salt water hot tub before you add a shock to the water.

Related Read >>> How to Lower Salt Levels in a Hot Tub?

Calculate How Many Gallons of Water Is in the Salt Water Hot Tub

Hot tub shock either chlorine or non-chlorine shock should be added to the water in the right amount. To know the right amount of chlorine shock needed, you first need to know the amount of water in your hot tub.

The amount of water determines the amount of hot tub shock that you need to add to the salt water hot tub. Here is an estimate to help you out.

Calculate the Amount of Hot Tub Shock Needed

When you know the amount of water inside the hot tub, you can calculate how much shock you should add to the salt water. Hot tub shocks usually have detailed instructions on how much shock should be added per liter or gallon.

The usual instruction is to add 35 grams of chlorine shock to 1500 liters of water (or 396 gallons of water). However, this instruction will vary based on the type of chlorine shock you are using so follow the instructions.

Related Read >>> How To Clean a Salt Water Hot Tub?

Shock the Salt Water Hot Tub

After you checked the water chemistry levels, you need to shock the salt water hot tub.

When you know the right amount of chlorine shock needed, you can add it to the salt water hot tub. If you have a vinyl or fiberglass hot tub, you might need to dilute or mix the chlorine shock first before adding it to the hot tub.

Adding the shock directly to a vinyl or fiberglass salt water hot tub can cause discoloration and stains on the shell of the hot tub.

Turn on the Jets on a Low Setting

After you have added the shock to the salt water hot tub, you need to turn on the jets but ensure they are switched on a low setting. On your hot tub control panel, pressing the jet button once will turn on the jets on a low setting.

Alternatively, you can just turn on the circulation pump and turn off the jets. After adding the shock, the water needs to be circulated gently so the chlorine can be well-absorbed by the water. The jets on a low setting or the circulation pump will circulate the water properly and give you the best results.

Leave the Hot Tub Open

As the chlorine shocks the salt water hot tub, there would be gases that would be released. You need to leave the hot tub open so the gases can escape.

Filter the Debris

A few hours after shocking the salt water hot tub, you might notice a few debris floating on the surface of the water. Use a net to scoop out the debris. You might also notice that the water is a bit cloudy. This usually means that the shock has killed the algae in the hot tub. You should also use a net to scoop out the dead algae.

Test the Water Again And You Are Done

You should turn on the jets and let the water circulate for about 20 minutes so the filtration system can pick up any contaminant in the water. After that, you can also add a line flush to the water to flush out the biofilm in the plumbing lines.

Once you shock the hot tub, and some time has passed by. You need to re-test your hot tub levels to see if the shocking process worked.

After the salt water hot tub has been shocked, you need to test the water to be sure the water chemistry is right. If the chemical properties and chlorine in the hot tub are right, then that means you have successfully shocked the salt water hot tub.

You should also leave the chlorinator off for a few days after shocking the hot tub. You will surely have enough chlorine in your hot tub after shocking it so you don’t need the chlorinator for a few days.

Can I Shock a Salt Water Hot Tub the Same Way I Shock a Regular Hot Tub?

You can shock a salt water hot tub the same way you shock a regular hot tub. To shock a chlorine hot tub, you can follow the same procedure as discussed above for shocking a salt water hot tub. The only difference is that salt water hot tub might require more chlorine than regular hot tubs.

Regular chlorine-based hot tubs usually have more chlorine in them than salt water hot tubs. So, there might be a variation in how much chlorine you will add to your salt water hot tub.

Shocking a hot tub is the same thing either you use a chlorine hot tub or a salt water hot tub. A salt water hot tub is practically the same thing as a regular hot tub. They both use chlorine as a sanitizer to make the water clean and healthy. The only difference is in how the chlorine is added to the water.

This means you can shock your salt water hot tub the same way you shock your regular hot tub but not with the same quantity.

Related Read >>> Salt Water vs Chlorine Hot Tubs

How Long Does It Take to Shock a Salt Water Hot Tub?

There is no specific time limit for hot tub shock to work in a salt water hot tub. The shocking process is also called oxidization and it can take between 15 minutes and a few hours to shock or oxidize a salt water hot tub.

It takes up to 15 minutes to a few hours for the shock process to do its thing.

The time it takes to shock a salt water hot tub depends on how much shock you added to the salt water hot tub and the size of the salt water hot tub. For instance, it would take a few hours to properly shock a 6 person salt water hot tub while a 3 person salt water hot tub can be shocked in less than 30 minutes.

How Often Should You Shock a Salt Water Hot Tub?

A salt water hot tub should be shocked at least once in two weeks. A salt water hot tub constantly has chlorine in the water which is a big advantage. The chlorinator adds chlorine to the water at regular intervals which means your hot tub is not unprotected.

So, unless there is a severe case of algae bloom or hot tub scum in the salt water hot tub, you should shock the salt water hot tub once in two weeks.

Another alternative to know when to shock your salt water hot tub is to test the water. You should test the water for both free chlorine (or unused chlorine) and combined chlorine (or used chlorine). If the combined chlorine level is above 0.5ppm (parts per million), then that means there is too much scum in the water and the chlorine is being used up quickly.

That usually means you need to shock the salt water hot tub. But if the free chlorine in the hot tub is between 1.5ppm and 3ppm, that means there is enough active chlorine in the water to fight any contaminant. In other words, you don’t have to shock the salt water hot tub.

How Long Do You Have to Wait After Shocking a Salt Water Hot Tub Before Using It?

It is usually best to wait between 24 hours and 48 hours after shocking a salt water hot tub before using it. This is because shocking the hot tub increases the chlorine content in the water. In other words, shocking the salt water hot tub makes the water more acidic. So you should not soak in it yet.

The way the chlorine shock works is when it is added to the water, it kills the algae, bacteria, and removes the scum in the water. As the chlorine shock does this, it is gradually being used up and the acidic level of the water is being lowered. You need to wait till the chlorine level is below 4ppm before you can soak in it again.

So, the right way to be sure you can soak in your salt water hot tub after shocking it is to test the water for chlorine level. If the chlorine level is below 4ppm and the water chemistry is right, then you can soak in it.

Final Words

Overall, shocking your salt water hot tub is something you should do more often than not. It ensures the water remains safe and it also complements the efforts of the chlorinator in keeping the salt water hot tub safe. Just ensure you add the right dose and you are good to go.

So there you have it. Now you know why and how to shock a salt water hot tub. If you liked this post, ensure to check out other posts on this website for more hot tub tips. Have a nice day.

Hi, I'm Calvin Hall, the owner of Hot Tub Wiki. I worked at a local Spa Service for a few years before creating this website. I have owned several hot tubs and fixed a thousand of them. So, I know a thing or two about hot tubs.