You'll see three ways to add things. The method isn't fussiness — it's what keeps a chemical from damaging your surface or just sitting on the floor doing nothing.
Knowing which product to reach for is half of it. The other half is how much — and that depends on your pool’s gallons and today’s readings, not on the label. Put your numbers into the free calculator and it names the product and the exact amount. No account needed.
Liquid chlorine (10% / 12.5%)
The everyday way to raise sanitizer fast.
Raises free chlorinePour-in liquid
Adds free chlorine immediately, with no leftover stabilizer or calcium. The most common way to keep a pool sanitized day to day.
How you add it. With the pump running, pour it slowly around the perimeter of the deep end. It mixes in within an hour.
Why this way. It's already liquid, so it disperses instantly — no dissolving needed. Pouring with the pump on spreads it evenly instead of letting a strong slug sit in one spot and bleach the surface.
Safety- Strong oxidizer — wear gloves and eye protection.
- Add with the pump running; never combine with acid.
- Always follow the product label.
Calcium hypochlorite (Cal-Hypo 65%)
A granular chlorine that packs a punch — and a little calcium.
Raises free chlorine (and water hardness)Pre-dissolve first
A powdered chlorine often used to shock a pool. It raises free chlorine strongly and also adds a bit of water hardness.
How you add it. Pre-dissolve in a bucket of warm water, let the undissolved bits settle, then pour the liquid around the pool with the pump running. Add at dusk so sunlight does not waste it.
Why this way. Granular chlorine that sinks before dissolving can bleach or pit the floor. Pre-dissolving turns it into an even liquid first. Because it also adds calcium, it is a poor fit for pools that already run hard.
Safety- Strong oxidizer — pre-dissolve in a bucket of warm water.
- Adds calcium; avoid in pools with already-high water hardness.
- Always follow the product label.
Muriatic acid (31.45%)
The standard way to bring pH (and alkalinity) down.
Lowers pH and alkalinityPour-in liquid
A strong liquid acid that lowers pH and alkalinity together. The workhorse for high-pH water.
How you add it. With the pump running, pour slowly into the deep end while walking along the edge to spread it out. Add to water — never add water to acid.
Why this way. Acid is heavy and concentrated; pouring it in one spot creates a pocket of very low pH that can etch surfaces. Distributing it with circulation on lets it blend safely. The "acid to water" rule prevents a violent reaction.
Safety- Highly corrosive; wear gloves, eye protection, and add to water (never water to acid).
- Apply with pump running, distributed across the pool.
- Always follow the product label.
Dry acid (sodium bisulfate)
A granular, gentler-to-handle way to lower pH.
Lowers pH and alkalinityPre-dissolve first
A powdered acid that lowers pH and alkalinity, like muriatic acid but easier and safer to handle.
How you add it. Pre-dissolve in a bucket of water, then pour around the pool with the pump running.
Why this way. Pre-dissolving avoids a low-pH pocket settling on the floor and keeps the dose even. Many owners prefer it to liquid acid because there are no corrosive fumes to manage — handy in tight or indoor spaces.
Safety- Less hazardous than muriatic acid but still corrosive — wear gloves.
- Pre-dissolve in water before adding to the pool.
- Always follow the product label.
Soda ash (sodium carbonate)
Raises pH quickly when water turns too acidic.
Raises pH and alkalinityPre-dissolve first
A granular base that raises pH, with a meaningful bump to alkalinity too. The go-to when pH has dropped low.
How you add it. Pre-dissolve in warm water and add slowly with the pump running. Going slow prevents a cloudy bloom.
Why this way. Dumped in dry, soda ash can briefly cloud the water as it reacts. Pre-dissolving and adding gradually keeps the water clear and the rise gentle and controllable.
Safety- Strongly alkaline — wear gloves and keep the dust out of your eyes.
- Pre-dissolve in warm water; add slowly to avoid cloudiness.
- Always follow the product label.
Borax
Nudges pH up without piling on alkalinity.
Raises pH (minimal alkalinity change)Pre-dissolve first
Raises pH with very little effect on alkalinity — useful when pH is low but alkalinity is already fine.
How you add it. Pre-dissolve before adding, then distribute with the pump running.
Why this way. Choosing borax over soda ash is about precision: when you only want to move pH and not alkalinity, borax lets you adjust one dial without disturbing the other.
Safety- Harmful if swallowed — keep away from children and pets.
- Adds borates; raises pH with minimal alkalinity impact.
- Pre-dissolve before adding.
- Always follow the product label.
Baking soda (sodium bicarbonate)
Raises alkalinity with barely a nudge to pH.
Raises alkalinityBroadcast across surface
The same baking soda from the kitchen, in bulk. Raises alkalinity while leaving pH almost untouched.
How you add it. Broadcast slowly across the surface with the pump running. It dissolves readily and needs no bucket.
Why this way. Because it dissolves easily and barely moves pH, you can sprinkle it straight in. This is the tool for fixing low alkalinity first, before you fine-tune pH.
Safety- Low-hazard and gentle to handle — just keep the dust out of your eyes.
- Add slowly with the pump running; minimal pH effect.
- Always follow the product label.
Calcium chloride
Adds calcium to protect plaster and surfaces.
Raises water hardnessPre-dissolve first
Raises water hardness — used when soft water threatens to etch your surfaces.
How you add it. Pre-dissolve in warm water (it warms up as it dissolves — that is normal), add slowly, and brush to help it disperse.
Why this way. Calcium chloride releases heat as it dissolves, so adding it to a bucket first keeps that reaction away from your pool surface and avoids a hot, concentrated spot.
Safety- Pre-dissolve in warm water; the reaction is exothermic.
- Add slowly; brush to dissolve.
- Always follow the product label.
Stabilizer (cyanuric acid)
Adds the 'sunscreen' that makes chlorine last.
Raises stabilizer (CYA)Pre-dissolve first
Raises stabilizer so sunlight stops burning off your chlorine so fast. A little goes a long way and it is slow to leave.
How you add it. Pre-dissolve in a bucket of warm water before adding, then give it up to a week for the reading to fully settle. Resist the urge to add more before then.
Why this way. Stabilizer dissolves very slowly. If you dump it in dry it can sit in the skimmer or on the floor for days. The slow change is also why patience matters — adding more too soon is the usual cause of overshooting, and a high stabilizer level can only be fixed by draining water.
Safety- Mild eye and skin irritant — wear gloves and avoid breathing the dust.
- Pre-dissolve in a bucket of warm water before adding to the pool.
- Stabilizer dissolves slowly; allow up to a week for full reading change.
- Always follow the product label.
Pool salt
The fuel for a saltwater chlorine generator.
Raises saltBroadcast across surface
Raises the salt level so a salt-chlorine generator can make its own chlorine. Only needed on saltwater systems.
How you add it. Broadcast across the pool with the pump running and brush to dissolve. Add gradually over a day and retest before adding more.
Why this way. Salt takes hours to fully dissolve and circulate, so adding it gradually keeps you from overshooting — and the only way to lower salt is to drain and refill. Use sodium-chloride pool salt only, never road or rock salt.
Safety- Use sodium-chloride pool salt only — never road salt or rock salt.
- Add with the pump running; brush to dissolve.
- Always follow the product label.
