Pool Stabilised Chlorine Granules

Stabilised chlorine granules (SDIC) for swimming pools. Dissolve in seconds and add 1 ppm of free chlorine per 14 g per m³ without raising pH. The go-to fast top-up granule for outdoor pools.

• Adds 1 ppm of free chlorine per 14 g per m³.
• Dissolves fully in 30-60 seconds with no residue.
• pH-neutral so balance is preserved after dosing.
• Built-in cyanuric acid keeps chlorine UV-stable outdoors.
• Suitable for daily top-ups, weekly shocks and post-fill chlorination.

Sizes and prices

• 5kg: £34.50
• 10kg: £68.13
• 25kg: £169.00

When you need it

• Free chlorine has dropped below 1 ppm and you need a fast top-up.
• Heavy bather load over the weekend has burnt off your reservoir.
• You want to chlorinate after a fresh fill or part-drain.
• You want pH stability that TCCA tablets do not give.
• You need a granule that dissolves cleanly without staining vinyl.

How to use

1. Test free chlorine, pH and alkalinity.
2. Confirm pH 7.2-7.6 and TA 80-120 ppm before dosing.
3. Pre-dissolve the dose in a 10 L bucket of pool water and stir.
4. Switch the pump to filtration and pour the solution slowly across the deep end.
5. Run circulation for at least 4 hours after dosing.
6. Test free chlorine and wait until below 5 ppm before swimming.

Dosing guide

Doses are starting points; always retest after 4 hours and adjust. SDIC adds approximately 6 ppm of cyanuric acid per 10 ppm of chlorine dosed, so monitor CYA every fortnight.

• For 20 m³, add 280 g to reach Raise 1 ppm chlorine.
• For 40 m³, add 560 g to reach Raise 1 ppm chlorine.
• For 60 m³, add 840 g to reach Raise 1 ppm chlorine.
• For 40 m³, add 2.8 kg to reach Weekly shock to 5 ppm.
• For 60 m³, add 8.4 kg to reach Algae shock to 10 ppm.

How it works

Sodium dichloroisocyanurate dihydrate (SDIC) at 56% available chlorine, with built-in cyanuric acid stabiliser.

SDIC dissolves to release hypochlorous acid (HOCl), the active sanitiser, plus cyanurate which protects spare chlorine from UV destruction. The pH at point-of-dose is close to neutral so pool balance is not disturbed.

SDIC is the only fast-acting stabilised chlorine. Cal-hypo is fast but raises pH and adds calcium; liquid chlorine is fast but knocks pH up too. SDIC is the clean, no-side-effect daily top-up.

Frequently asked questions

How much do I dose?

14 g per m³ raises free chlorine by 1 ppm. For a 40 m³ pool that is around 560 g per ppm.

Do I need to pre-dissolve?

Yes for vinyl pools. For tile or concrete pools you can broadcast across the deep end with circulation running.

When can people swim again?

Once free chlorine drops below 5 ppm; usually 2-4 hours after dosing with circulation on.

How long does a 5 kg pack last?

About 9 weeks of daily 1 ppm top-ups for a 40 m³ pool, longer in cool weather.

Will SDIC raise my pH?

No. SDIC dissolves close to neutral pH; that is its main advantage over cal-hypo and liquid chlorine.

Is it OK for vinyl liners?

Yes, provided you pre-dissolve in a bucket. Never let dry granules sit on the liner.

What is the active ingredient?

Sodium dichloroisocyanurate dihydrate (SDIC) at 56% available chlorine with built-in stabiliser.

How much CYA does it add?

About 6 ppm of cyanuric acid for every 10 ppm of free chlorine dosed.

Why does pH stay neutral?

SDIC dissolves with a near-neutral hydrolysis profile, unlike cal-hypo which is alkaline and TCCA which is acidic.

Chlorine demand will not budge?

You have an algae bloom; shock to 10 ppm with cal-hypo.

CYA too high?

Drain and refill; SDIC keeps adding stabiliser with every dose.

SDIC vs TCCA tablets?

Granules dose in seconds for fast top-ups; tablets feed slowly through a skimmer for unattended sanitising.

SDIC vs cal-hypo?

SDIC is pH-neutral and stabilised; cal-hypo is alkaline and unstabilised. Use SDIC for routine topping, cal-hypo for shocks.