Pool chemicals explained: what each one does, when to use it
The pool chemical aisle has 30+ products with overlapping names. Most pool owners only need 5 of them. Here’s what each does, when you need it, and which ones are just expensive marketing for chemicals you already have.
Last updated: 2 June 2026
The pool chemical aisle has more products than the average pool owner needs. There are 8 different chlorine products that all do the same thing differently, 4 pH adjusters, 3 alkalinity products, and dozens of “specialty” products with overlapping functions. Most residential pools need 5 chemicals, maybe 7. Most pool owners buy 15+.
This guide is a glossary of the chemicals you’ll actually encounter, what each does, when you need them, and which ones are unnecessary purchases.
The 5 essential pool chemicals
| Chemical | Function | Australian product name(s) |
|---|---|---|
| Liquid chlorine | Primary sanitiser | “Pool chlorine”, “Sodium hypochlorite 12.5%” |
| Muriatic acid | Lowers pH and alkalinity | “Pool acid”, “Hydrochloric acid 32%” |
| Sodium bicarbonate | Raises alkalinity | “Pool alkalinity up”, “Bicarb soda” |
| Cyanuric acid | Stabilises chlorine against UV | “Pool stabiliser”, “Pool conditioner” |
| Calcium chloride | Raises calcium hardness | “Pool hardener”, “Calcium up” |
With these five, you can manage every chemistry parameter in a typical residential pool. Everything else on the pool store shelf is optional.
Chlorine products, what each one actually is
| Product | Chemistry | Active chlorine % | Adds CYA? | Best for |
|---|---|---|---|---|
| Liquid chlorine | Sodium hypochlorite NaOCl 12.5% | 12.5% | No | Daily dosing, no CYA build-up |
| Cal-hypo granular | Calcium hypochlorite Ca(OCl)₂ | 65–73% | No (raises CH) | Daily dosing, where calcium is low |
| Dichlor granular | Sodium dichloroisocyanurate | 62% | Yes (~57%) | Quick shock, occasional use |
| Trichlor tablets | Trichloroisocyanuric acid | 90% | Yes (~54%) | Slow-release feeder use early season |
| Saltwater (SWG-generated) | Sodium hypochlorite (generated from NaCl) | n/a (on-demand) | No | Year-round automated chlorination |
The honest summary: liquid chlorine is the simplest, cleanest residential chlorine. No CYA build-up, no other chemicals introduced. The trade-off is bottles are heavy and lose 5–10% strength per month in storage.
pH adjusters
| Product | Function | Australian dose for 50,000 L |
|---|---|---|
| Muriatic acid (32% HCl) | Lowers pH (and TA slightly) | ~275 mL per 0.2 pH drop |
| Dry acid (sodium bisulfate) | Lowers pH | ~380 g per 0.2 pH drop |
| Soda ash (sodium carbonate) | Raises pH | ~350 g per 0.2 pH rise |
| Sodium bicarbonate (baking soda) | Raises TA, slight pH increase | ~1.4 kg per 10 ppm TA rise |
Salt products (saltwater pools)
| Product | Use |
|---|---|
| Pool salt (pure NaCl) | Salt cell fuel, only buy this type |
| Solar salt | Acceptable alternative, marginally cheaper |
| Rock salt, table salt, sea salt | DON’T USE, impurities damage cells |
Stabiliser products
Sold as “stabiliser”, “conditioner”, “pool conditioner”, or “cyanuric acid”. All the same chemical (cyanuric acid). The “long-lasting chlorine” products contain CYA built into the chlorine, convenient initially but causes CYA build-up over time.
Calcium hardness products
| Product | Use |
|---|---|
| Calcium chloride | Raises CH, about 12 g per 10 ppm in 1,000 L |
| Calcium hypochlorite (cal-hypo) | Adds chlorine AND CH (incidental side effect) |
| “Calcium reducer” products | Marginal effectiveness, usually drain is the real fix |
Algaecides, what’s worth it and what isn’t
| Product | Effective against | Use case |
|---|---|---|
| Polyquat (poly hexamethylene biguanide) | Green algae prevention | Best routine preventive. No staining. |
| Copper-based algaecide | Black algae, severe green | Active treatment only. Can stain plaster. |
| Sodium bromide | Yellow/mustard algae | Specific use case only. |
| “Silver-based” or “mineral” algaecides | Marketing | Largely ineffective. Skip. |
“Specialty” products you probably don’t need
- “Pool clarifier”, only useful for fine particulate after storms. Not a routine product.
- “Pool flocculant”, drops particulates to floor for vacuum. Niche use.
- “Pool defoamer”, masks foam temporarily but doesn’t fix cause. See our foam guide for real fixes.
- “Stain & scale inhibitor”, useful for pre-fill water that’s high in metals (well water). Not needed for municipal water.
- “Phosphate remover”, phosphate as algae food is overrated. Most pools don’t need this.
- “Tile cleaner”, usually just mild acid. Use muriatic acid you already have, diluted.
- “Pool shock” (branded products), usually just dichlor granular or cal-hypo at 3× the price.
Buying tips
- Buy core chemicals in bulk. 20kg bags of pool salt are cheaper per kg than 5kg bags. Liquid chlorine in 20L containers is cheaper per litre than 5L bottles.
- Skip pool store markup on basics. Sodium bicarbonate at the supermarket (baking soda) is identical to pool-store “alkalinity up”. Calcium chloride for ice melting is identical to pool calcium hardener.
- Use the right chlorine for the use case. Liquid for routine daily, cal-hypo for occasional shock, trichlor only sparingly or as feeder.
- Store chemicals properly. Cool, dry, sealed. Chlorine loses strength in heat. Muriatic acid fumes corrode metal.
Sources & references
- Trouble Free Pool, ABCs of Pool Water Chemistry
- ANSI/APSP-11, Water Quality Standards in Public Pools
- AS 3633-1989, Private swimming pools (Australian Standard)
- CDC Healthy Swimming guidance
Frequently asked questions
What pool chemicals do I actually need?
Five essentials: liquid chlorine (sanitiser), muriatic acid (lower pH), sodium bicarbonate (raise alkalinity), cyanuric acid (stabilise chlorine), and calcium chloride (raise hardness). With these five, you can manage any chemistry issue in a typical residential pool. Salt chlorinator owners add pool-grade salt to the list.
Is baking soda the same as pool alkalinity up?
Yes. Both are sodium bicarbonate (NaHCO₃). Pool-store packaging is marked up; food-grade baking soda from the supermarket is identical chemistry. Just be sure it’s sodium bicarbonate, not sodium carbonate (which is washing soda and raises pH instead).
Should I use trichlor tablets or liquid chlorine?
Liquid chlorine for daily dosing, clean, no CYA build-up. Trichlor tablets only as occasional feeder use, especially early in the season when CYA is low. Long-term trichlor use leads to chlorine lock as CYA accumulates.
Do I need ‘pool clarifier’ regularly?
No. Clarifier is for fine particulate after storms or pollen events. Not a routine product. If your pool is constantly cloudy, the underlying chemistry issue needs addressing, not a clarifier mask.
Is salt the same as pool salt?
No, only use pool-grade salt (pure NaCl) in saltwater pools. Iodised table salt contains iodine and anti-caking that damage salt cells. Rock salt is too impure. Pool salt is sold in 20kg bags at pool stores and hardware shops.
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