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Castle Hot Tubs
Sep 21, 2021

The Shocking Truth About Hot Tubs

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Shock dosing with chlorine shock or non chlorine shock

Let’s face it, neither the term “shock” or “dose” are words that we associate with particularly pleasant events.  You might have heard that it is sometimes necessary to “Shock Dose” as part of your water treatment routine for your hot tub / spa or swimming pool.  Is this a bad thing?  Does it mean you’ve failed as a responsible hot tub owner?  We investigate and explain the shocking truth!

What is shock dosing?

What is chlorine shock dosing?

A chlorine shock dose is when you add a larger quantity of chlorine to your hot tub water in order to break down waste products and contamination in order to re-establish clean water.

What is non-chlorine shock dosing?

Non-chlorine shock doesn’t contain chlorine itself, and does not disinfect the water. Non-chlorine shock helps the chlorine already in your hot tub work better by oxidising the water and creating “free chlorine” – which is what is needed to kill bacteria. For those using bromine as a sanitiser, Non-chlorine shock will also activate bromine, helping it work more effectively.

 

Why do I need to shock dose my hot tub water?

Shock dosing your hot tub water will help to prevent the build-up of bacteria, viruses and algae and it will prolong the life of your spa.

 

What are the benefits of shock dosing my hot tub?

Shock dosing your hot tub water will keep it clear, clean safe and comfortable to use for longer.  It helps reduce the need for excessive draining and re-filling of your hot tub.

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When should I shock dose my hot tub water?

  • Before use, on the first fill of your hot tub
  • Any subsequent drain and re-fill
  • At the first sign of any algae or slime
  • After a period of heavy usage
  • After any loss of water clarity
  • If the hot tub hasn’t been used for a while
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Should I use a chlorine shock or a non-chlorine shock?

Chlorine shock is suitable for commissioning a new hot tub, after a fresh water change or after very heavy use. Because it will raise chlorine levels you may have to wait for the chlorine level to reduce before you can allow bathers to safely use the hot tub. If you use Bromine as a sanitiser, you cannot use chlorine shock.

Non-chlorine shock does not disinfect the water, it helps the existing sanitiser (chlorine or bromine) to work better and more effectively. You can generally use the hot tub sooner after adding non-chlorine shock.

Is it safe to chlorine shock dose my hot tub water?

Shocking your spa water is an important part of your maintenance routine. But high chlorine levels can be dangerous, so it is very important that no bathers are in the water when adding chemicals. To ensure that the water is safe, ensure that chlorine levels have dropped below 5ppm before allowing bathers back into the water. Chlorine levels should be checked with test strips or a digital test reader.

How do I Chlorine Shock Dose my hot tub?

Dissolve the chlorine shock granules. Add the chlorine shock mixture directly to the water with the filtration / circulation pumps running. Never shock dose the water with the circulation turned off. Leave the hot tub cover off for at least 20 minutes. This will prevent chemical damage to the cover and pillows of your hot tub.

My hot tub water smells strongly of chlorine what should I do?

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When chlorine combines with organic waste (body fluids, dead skin etc) it produces a compound called chloramine. This gives off a strong chlorine odour. This is often mistaken for too much chlorine but is in fact an indication that the chlorine has been “used” up. A shock treatment will breakdown chloramine so it can be easily removed from the water, “freeing up” your chlorine to work more effectively.

My hot tub water is cloudy what should I do?

Us humans carry organic compounds on our skin, such as oils, cosmetics, lotions and dead skin itself. This quickly accumulates in hot tub water and can cause it to become cloudy. Shock dosing the water will help to remove these compounds and assist in clarifying and cleaning the water.

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We hope you have found our guide to shock dosing your hot tub, swimming pool or spa useful. So don’t let the name put you off, it’s an important part of your water care routine.  Used properly, shock dosing can help you maintain pure and clear water just like in the photo above!  Check our blogs regularly as we continue to add to our Water Quality FAQs!