Description
HTH Premium Chlorine Shock is a fast-acting, calcium hypochlorite-based shock treatment for swimming pools, supplied as a 5kg pack. Shock dosing forms an essential part of pool maintenance, used to quickly raise free chlorine levels, break down chloramines, kill algae and restore clarity after heavy use or warm spells.
This high-strength formula works quickly once added to the water, making it effective both for reactive treatment when water quality drops and for planned weekly or fortnightly shock dosing as part of a regular maintenance routine. The fast-dissolving granules spread evenly through the pool, so normal use can resume as soon as chlorine levels are back within the recommended range.
Main features:
- Fast-acting calcium hypochlorite formula gives a rapid chlorine boost
- Effectively kills bacteria, viruses and algae
- Breaks down chloramines to bring back fresh, clear water
- Suited to both reactive shock treatment and planned maintenance dosing
- Fast-dissolving granules ensure even distribution
- Supplied as a 5kg pack suited to regular pool maintenance
- Works with standard pool dosing equipment
Always test pool water before and after shock dosing. Shock at dusk or after bathers have left, and do not allow swimming until chlorine levels have returned to 1 to 3 ppm. Wear appropriate PPE when handling pool chemicals.







Katrina –
Good service
frauU –
Must have for pools
Caroline Marks –
Good product
action man –
To reduce pool problem and clear murky water
Donna Bennett –
Its chlorine shcok granules
m.lad (verified owner) –
Did the trick!
Fabrizio T. –
Always use this now :
G. R. Hough (verified owner) –
Speedy delivery
Mindfulness&Tranquillity –
Quick and easy to use
Peter Lomax (verified owner) –
I have been using it for many years.
Imogen Sharples –
It is just great.
Andrew Sixsmith (verified owner) –
The pool was quickly good and clean again.
Barry Winstanley –
Good quality product.
Martin Hedley (verified owner) –
A very good product that I have used for several years, both as a shock treatment and for routine maintenance.
Melanie Ollerhead (verified owner) –
We have always used this chlorine. It is the best and our water is always clean and clear. I would happily buy it again.
Frank Bardsley –
Good price, good product.
Toby Hindle –
I use this so the stabiliser level does not get too high, alternating with stabilised chlorine, at between 50 and 100g a day. Very effective and I have never had a water quality problem. One thing to watch is that it can push the pH up, so keep some pH minus in stock to stay below 7.4.
Patricia Garside –
An easy product to use.
Tony Greenhalgh –
Very well packaged.
Damian Rossiter (verified owner) –
Easy to use and it does not cause chlorine lock.
Adrian Pemberton (verified owner) –
Always top quality.
Stanley Redfern –
Very easy to use.
Doreen Sagar (verified owner) –
Great product, very effective.
Norah Kenyon (verified owner) –
Yes, it works just as it should.
Rhona Tickle –
A product that does its job.
Denise Rushworth (verified owner) –
We have had our pool for over ten years and never had green water. Last year it happened twice, and acting quickly with this shock treatment sorted it out.
Clive Hargreaves –
A great brand.
Lesley Rowntree –
A very good product that met my expectations.
Bethan Lofthouse (verified owner) –
The best chlorine I have tried.