Shock dosing a Lay-Z-Spa refers to adding a larger quantity of chlorine to your water in order to break down any organic waste and contamination and re-establish a positive level of water cleanliness.
A shock dose is performed using chlorine granules, but not chlorine tablets . Tablets are slow-releasing and used to maintain the correct daily chlorine level.

When Do I Need To Shock My Hot Tub Water?
Your Lay-Z-Spa hot tub water should be shocked when:
- You first fill up your Lay-Z-Spa
- At the first signs of algae or slime
- After periods of heavy usage
- After a loss of water clarity or quality
- After refilling with fresh water
How Often Should I Shock My Hot Tub Water?
It is good practice to shock dose hot tub water with ClearWater Chlorine Granules after a period of high usage. This will help to rectify the sanitizer level, prevent the growth of microorganisms and help maintain sparkling, crystal clear water. After treatment, water quality and clarity is often completely restored.
How To Shock Dose A Hot Tub
Shocking your hot tub is essential for hot tub maintenance by helping to prevent the buildup of bacteria. By shock dosing your hot tub, it reduces the need for high chemical doses; aids in eliminating bacteria, viruses, and algae; and prolongs the life of your spa. Experts recommend shocking your hot tub before first use and then at least once a week.
To shock dose, follow these five steps:
- Ensure that your spa is filled with water up to the recommended level.
- Turn on the Water Filtration System but ensure the massage system is turned off.
- Check the water capacity of your hot tub. The size of your hot tub will impact just how much chlorine you need to add to your spa. Dilute the chlorine in a jug of warm water and pour into your hot tub with the filter on.
🔎 Chlorine Dosage Guide (skip down the page for Shock Dose Guide)
- After giving a shock treatment to your Lay-Z-Spa water, wait for a minimum of 24hrs then test the chlorine level. You can start using your Lay-Z-Spa when the chlorine level is 5ppm or less (ideal 3-5ppm), but not before completing step 5.
- If needed, no balance your Total Alkalinity and pH.
After shock dosing a Lay-Z-Spa
Following a shock dose, it is important that you continue to monitor the chemical levels of your hot tub to ensure the chlorine stays at the recommended levels. This page shows some guidance as to the recommended dosage amounts for each of the Lay-Z-Spa models. We recommend using a ClearWater Dip Test Strip to monitor your hot tub's chlorine, Alkaline and pH levels.
From reducing chlorine levels to preventing cloudy water, explore our frequently asked chemical-related questions on shock dosing your Lay-Z-Spa by visiting our Chemical Guide. If you need more hot tub chemicals, explore the ClearWater Chemicals Range.