When and How Often to Shock a Hot Tub




Shocking your hot tub is important and should be a regular part of your hot tub maintenance routine.

The amount of water in a hot tub is relatively small (when compared to a swimming pool) so the levels of contaminants can increase very quickly if you use the hot tub frequently.

Shocking is the way to deal with this, along with keeping the pH and sanitizer levels correct.

Knowing how to shock is all very well but how do you know how often to shock your hot tub or when to shock a hot tub?

Hopefully, this article will help you decide.

How often to shock hot tub

How often should you shock your hot tub?

The opinions on how often to shock hot tub water are divided. Some say hot tubs should be shocked every week, others say twice per week, while others recommend using hot tub shocks at least once every two weeks. One thing is clear, you should do it on a regular basis.

It really depends on how often you use the spa, how many use it, where it is situated, the water temperature, etc.

You should test the water in your hot tub often, particularly when you are new to owning one, as this will give a good indication of how often should you shock a hot tub. You should use good quality water test strips such as the Aquachek 7-way test strips. These work for both chlorine and bromine hot tubs.

Recommended Test Strips

AquaChek 7-Way Pool and Spa Test Strips - Silver Pool Test Strips For pH, Total Chlorine, Free Chlorine, Bromine, Alkalinity, Total Hardness, and Cyanuric Acid - Water Quality Testing Kit (100 Strips)

Aquachek 7-way test strips

I use these test strips that can tell you the total chlorine/bromine, free chlorine, pH, total alkalinity, CYA and hardness levels.

Over time you will get to know what frequency works best for you depending on how often and how many people use it.

It is mainly me who uses our hot tub, and I use it around 3 times per week on average, so I generally give it a shock treatment around every 10-14 days. I test the water between times though.

In the end, it is important that you are bathing in clean water that does not make you sick. When the hot tub is used often, then using spa shock once a week is highly recommended.

Did you have lots of guests over so the spa has a high bather load? Then shocking it right after that occasion would be advisable so that the next time you go to your hot tub, you won’t find the water dirty and cloudy.

At the end of the day, if in doubt, shock!

When to shock hot tub?

If you are going to shock in order to correct a problem with the hot tub water, such as cloudy water or even signs of algae, then you should go ahead and shock the hot tub immediately. You do not want to waste a moment in getting the water back into good condition and delaying may make the situation worse.

If you are simply going to shock as part of your regular maintenance then the best time to do it is after you use it. This will give it time for the shock to do its work and then for the chemical levels to reduce to normal again ready for your next soak.

If you have just refilled the hot tub, after cleaning it, after it has been empty for a while or perhaps it is a new hot tub, then you should shock it as a matter of course.

Read my complete guide to How to Shock a Hot Tub

When to shock hot tub
Testng the hot tub water with a test strip

When can you go in again after shocking?

If using a chlorine-based shock you will need to wait longer to use the hot tub again than if you use a non-chlorine oxidizer shock.

Chlorine-based shock chemicals are not safe to bathe in while at a high concentration. They can be very harsh on the skin and bad for your lungs. The time to wait depends on the chlorine levels when you test the water but they can take 24 hours to reach a safe level.

When using non-chlorine shock you can use the tub again in as little as twenty minutes.

Always read the labels that are on the hot tub chemicals you buy. They will advise you how long it takes for the reaction to be complete and when it is safe to get back in.

Read: How long to wait after shocking a hot tub

Which type of shock to use for hot tubs?

The most usual type of hot tub shock to use with a chlorine hot tub is, unsurprisingly, chlorine.

The two main types of chlorine shock are dichlor shock (dichloroisocyanuric acid) and cal hypo (calcium hypochlorite).

Most brands of spa shock contain dichlor and that would be the type I would recommend. Cal hypo is more suitable for shocking swimming pools.

You can also use a non-chlorine shock which is known as an oxidizer. Using this type of shock means you can use the hot tub again much sooner than using chlorine shock.

In a bromine hot tub you can use either chlorine based or a non-chlorine based shocks. Personally, I would use a non-chlorine oxidizer shock once a week.

I recommend using SpaGuard Spa Shock or SpaGuard Spa Shock-Oxidizer

SpaGuard Enhanced Spa Shock 6#

SpaGuard Spa Shock-Oxidizer, 7lb

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When and How Often to Shock a Hot Tub 1

Why shock hot tubs?

Some people wonder why they should shock their hot tub when they use plenty of sanitizer weekly. Unfortunately, only using sanitizing products won’t eliminate some of the things in the water that a weekly shock will.

The chlorine you use regularly will be stabilized. This means it also includes CYA (cyanuric acid) which slows down the evaporation of chlorine from the hot tub’s water allowing it more time to work on sanitizing the water.

Chlorine shock is unstabilized so it acts quicker and dissipates quickly.

Shocking a hot tub has many benefits:

  • Shock treatment breaks down chloramines (or bromamines) which are basically chlorine/bromine molecules that have attached themselves to contaminents. It is these that give a hot tub that “chlorine swimming pool smell”. Without shocking, these will just continue to build up.
  • Everyone that jumps in your hot tub takes some sort of organic contaminants with them. Think of contaminants such as dead skin cells, hair, shampoo, sunscreen, perfumes, deodorants, oils, etc. Shock will help kill bacteria and keep the hot tub clean.
  • Shocking a hot tub will keep the water fresh and clear. (If the water is not clear, this is a good indication that the hot tub needs to be shocked.)
  • such as the pump and filters for example.
shocking a hot tub before a hot tub party

Should you shock before or after using the spa?

When people ask if they should shock before or after using the spa my answer is that both can be true.

Provided the spa water is in ok condition, so you are only intending to give the hot tub a shock as part of your weekly maintenance, if you are planning to get in soon, it is best to do it after spending some time in the water.

On the other hand, if you plan to bathe in a few hours, then shocking it before should not be a problem but you should test it to check the chlorine level first.

That being said, it is advised to shock the spa after you have used it. This will give the chemical reaction all the time it needs to clean the water and for it to get down to normal levels. The normal levels will be much easier on your skin.

What happens if you dont shock your hot tub?

If you never shock your hot tub then chloramines (or bromamines if you use bromine as a sanitizer) will continue to build up in the hot tub water.

This will mean the sanitizer you have will be much less effective at killing bacteria and other contaminants.

What causes alkalinity to drop in a hot tub?

How much chlorine to add to a hot tub

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