Pool chemicals · 次氯酸鈣
Calcium hypochlorite (shock)
Granular unstabilised chlorine for shock dosing and superchlorination — the reset button after contamination, algae or a failed water test.
(852) 5923 7263Request a quote
Granular unstabilised chlorine for shock dosing and superchlorination — the reset button after contamination, algae or a failed water test.
Calcium hypochlorite is the granular chlorine you reach for when the pool needs a lot of chlorine at once: shock dosing after contamination, an algae bloom or a failed test. It is unstabilised, so it adds no cyanuric acid — but it does add calcium over time, and it must never touch TCCA tablets or any other chlorine product.
Granular calcium hypochlorite — cal-hypo — one of the strongest solid chlorines in common pool use, typically 65–70% available chlorine (the exact strength is confirmed on quotation). Where slow-dissolve tablets are built for a steady trickle, cal-hypo is built for the opposite job: delivering a large, fast dose of chlorine when the pool needs superchlorination and then getting out of the way.
Because it is unstabilised, it carries no cyanuric acid — so a heavy shock dose won't push your stabiliser level up the way tablets would. That makes it the standard companion product for tablet-run pools: tablets for the everyday feed, cal-hypo for the occasional reset after an incident, visible algae, or a bacteriological result you didn't like.
| Form | Granules, for pre-dissolved shock dosing |
| Chemistry | Calcium hypochlorite (cal-hypo), unstabilised — typically 65–70% available chlorine, confirmed on quotation |
| Formats | Pack sizes confirmed on enquiry |
| Best for | Shock dosing and superchlorination after contamination, algae or a failed test |
| Price | Quoted on enquiry — we reply within one working day |
Standard practice is to dissolve the granules in a container of pool water first and dose the solution, rather than broadcasting dry granules — undissolved granules settling on a pool floor can bleach and etch the surface. Shock when the pool can rest afterwards, keep bathers out until chlorine returns to the normal band, and confirm with a test before reopening. Dosing is pool-specific: the dosing calculator gives a starting point for your volume, and laboratory testing tells you whether the shock did its job.
The long-term thing to watch is calcium. Every cal-hypo dose adds calcium hardness, and with regular use it climbs — eventually far enough to scale surfaces and heat exchangers. The water balance guide covers hardness alongside pH and alkalinity; routine testing keeps the trend visible before it becomes a problem.
Never mix cal-hypo with TCCA chlorine tablets. Calcium hypochlorite and trichloroisocyanuric acid react violently on contact — heat, toxic gases and a real risk of fire or explosion, even from residues left in a shared scoop, feeder or container. Use separate, labelled equipment for each product and never store them together. Safety. Cal-hypo is a strong oxidiser: store it cool, dry and sealed, away from acids, liquids, organic materials and every other chemical — never mix chlorine products, even their fumes. Keep away from children. Safety data sheets are available on request: see the SDS library.
Prices and pack sizes are confirmed on enquiry — we reply within one working day. Delivery across Hong Kong; ask about a standing delivery for estates and operators.
Gotech Chemical supplies granular calcium hypochlorite — typically 65–70% available chlorine, unstabilised — for shock dosing and superchlorination, delivered across Hong Kong. Pack sizes and prices are confirmed on enquiry; send the quantity on WhatsApp and we reply within one working day. Estates and operators can ask about a standing delivery.
After a contamination incident, after visible algae, after a failed water test, or when the water develops that sharp chloramine smell that means combined chlorine has climbed. Shock dosing (superchlorination) raises chlorine well above the everyday band for a short period to burn through contamination, then the pool is returned to service once levels fall back. Test before and after — a lab result tells you whether the shock actually worked.
In the same pool over time, yes — many pools run tablets day-to-day and cal-hypo for occasional shocks. But the two products must never physically meet: never in the same feeder, dispenser, scoop or container, and never stored together. Calcium hypochlorite and TCCA react violently on contact, with heat, toxic gas and a real risk of fire or explosion. Dedicate separate, labelled equipment to each.
Two ways. It is unstabilised, so it adds no cyanuric acid — which is exactly why it suits shock dosing. But every dose adds calcium, so with regular use calcium hardness climbs; over months that can push the water towards scale on surfaces and heat exchangers. Track hardness in your routine testing and rebalance when it drifts — our water balance guide explains what to watch.
Send us the pool size and a photo of what you use now — we'll tell you what to order. No obligation.