Non Chlorine Shock Granules

Weekly non-chlorine shock for hot tubs and spas. A potassium peroxymonosulfate (MPS) oxidiser that clears combined chlorine or bromine and lets bathers back in within 15 minutes.

• Clears combined chlorine and bromine in 15 minutes.
• Restores active sanitiser without dosing extra chlorine.
• Polishes water clarity after a heavy soak.
• Compatible with chlorine, bromine, MPS and salt systems.
• Safe to use just before guests arrive.

Sizes and prices

• 1kg: £18.83
• 2.5kg: £38.43
• 5kg: £71.09
• 10kg: £136.41
• 20kg: £267.06
• 25kg: £332.38

When you need it

• It is your weekly shock day.
• Combined chlorine reads above 0.5 ppm.
• Free chlorine has dropped fast despite recent dosing.
• Bathers report a chlorine smell or eye irritation.
• You want to restore clarity without raising chlorine.

How to use

1. Test free and combined sanitiser, pH and alkalinity.
2. Confirm pH 7.2-7.6 and alkalinity 80-120 ppm.
3. Pre-dissolve 17 g of MPS per 1000 L in 5 L of warm tub water.
4. Switch the pump to circulation and pour the solution across the surface.
5. Run circulation for 15-30 minutes uncovered.
6. Retest free chlorine and bromine; resume normal use once back in band.

Dosing guide

Standard weekly shock dose. After heavy bather events you can shock with the same dose at any time and bathe within 15 minutes.

• For 1,000 L (small spa), add 17 g to reach Weekly shock.
• For 1,500 L (typical hot tub), add 26 g to reach Weekly shock.
• For 2,000 L (large hot tub), add 34 g to reach Weekly shock.
• For 5,000 L (swim spa), add 85 g to reach Weekly shock.
• For 10,000 L (pool), add 170 g to reach Weekly shock.

How it works

Potassium peroxymonosulfate (potassium monopersulfate, MPS) compounded as a free-flowing granular oxidiser with at least 47% active KHSO5.

MPS releases peroxysulfate ions that selectively oxidise the nitrogen-rich combined chlorine (chloramines) and combined bromine (bromamines) into harmless gases and salts. This frees up the sanitiser bank, restores its active form and removes the eye-stinging by-products that build up over a week of use.

Free chlorine reads can mask high combined chlorine. Combined chlorine is the actual cause of chlorine smell, red eyes and dull water. Weekly MPS shock keeps combined sanitiser low and bather comfort high.

Frequently asked questions

How often should I shock?

Once a week as a routine; after any heavy bather event as needed.

How long until I can bathe?

15 minutes with the pump running and the cover off.

Does MPS replace chlorine or bromine?

No. MPS is an oxidiser, not a residual sanitiser. Continue chlorine or bromine for daily disinfection.

How long does a 1 kg pack last?

Around 38 weekly shocks for a 1500 L hot tub.

Is it safe for sensitive skin?

Yes. MPS forms few skin-irritant by-products and is the standard shock for sensitive bathers.

Will it work with bromine?

Yes. MPS clears combined bromine and reactivates the bromine bank for the next week.

What is MPS chemically?

Potassium peroxymonosulfate (KHSO5) at >= 47% active.

Why does MPS not raise chlorine?

MPS oxidises directly without donating chlorine atoms; sanitiser stays at the same chlorine level after dosing.

Does MPS raise total dissolved solids?

Yes. 17 g per 1000 L adds about 12 ppm sulphate. Refresh part of the water if sulphate exceeds 300 ppm.

Combined chlorine still high?

Repeat dose at 25 g per 1000 L; clean cartridge overnight.

Cloudy water after shock?

Run filter 24 hours; dose Sparkle Clarifier.

False zero on chlorine test?

Wait 15 minutes after dosing; some DPD kits are interfered with by MPS.

MPS vs chlorine shock?

MPS clears combined chlorine without raising free chlorine; chlorine shock raises free chlorine to 10 ppm and forces a wait before bathing.

MPS vs ClO2?

MPS is a routine weekly oxidiser. ClO2 is a periodic biofilm-targeting deep clean.