Quick verdict
The standard fix for low pH — plain soda ash at a fair price. Add gradually and retest; overshooting is easy.
Ideal for
- Pools testing below 7.2 pH
- Correcting after acid overdose or heavy rain
- Any pool type including salt
Not ideal for
- Pools already at or above ideal pH
- Lowering pH (use pH Reducer instead)
The full picture
When pool pH drops below about 7.2, water turns aggressive: it corrodes metal fittings, etches plaster, and stings eyes. In The Swim pH Increaser is straight sodium carbonate (soda ash) that raises pH back into the ideal 7.4–7.6 range. It's the same chemical every brand sells under a dozen names, so buy on price and purity — this is 100% soda ash with no filler. Dose it gradually with the pump running and retest, since overshooting pH is as much a problem as low pH. A staple every pool owner ends up needing, especially after heavy rain or acid overcorrections.
In The Swim pH Increaser (Soda Ash, 25 lb) at a glance
- Type
- pH increaser (raises pH)
- How often
- As needed when pH is low
- Size / volume
- 25 lb
- Active ingredient
- 100% sodium carbonate (soda ash)
- Coverage
- ~6 oz per 10,000 gal raises pH modestly — dose gradually and retest
- Compatible pools
- All pool types, including salt
- Safety
- Add slowly to pool water (never water to chemical); keep from children; don’t mix with other chemicals.
- Storage
- Store cool, dry, and sealed; keep well away from acids.
Source: Compiled from manufacturer specifications, label directions, industry practice, and aggregated owner feedback. Follow label instructions; specs and prices change — confirm before buying.
This is a research-based review — our analysis draws on manufacturer specifications, manuals, warranty terms, and verified owner feedback rather than our own hands-on testing, and we note where a detail couldn't be confirmed. How we review
The in-depth review
When pool pH drops below about 7.2, water turns aggressive — corroding metal, etching plaster, and stinging eyes. In The Swim pH Increaser is the standard fix.
What it is
It's 100% sodium carbonate (soda ash), the same chemical every brand sells under different names. That's not a knock — it means you can buy on purity and price, and this is filler-free. It raises pH into the ideal 7.4–7.6 range, and a modest dose (around 6 oz per 10,000 gallons) moves the needle.
How to use it
Add it slowly with the pump running, wait a few hours, and retest. pH is genuinely easy to overshoot, so resist the urge to dump a big dose. If your pH keeps falling, the real fix is often alkalinity: get total alkalinity into the 80–120 ppm range and pH becomes far more stable, so you reach for this less often.
Who needs it
Any chlorine or salt pool that tests low on pH, especially after heavy rain, acidic fill water, or an acid overcorrection. Skip it if your pH is already in range, and reach for pH Reducer instead if you need to come down.
Performance breakdown
Research-based editorial judgments from specs, warranty terms, and verified owner feedback — not lab measurements. How we score
Pros and cons
What works
- Pure soda ash, no filler
- Cheap and universally available
- Works in all pool types
- Simple broadcast application
What doesn't
- Easy to overshoot pH
- Can cloud water if over-dosed
- Same chemical as cheaper generics
- Only raises pH (not alkalinity control)
Best alternatives to In The Swim pH Increaser (Soda Ash, 25 lb)
HTH
HTH Super Shock Treatment (Cal-Hypo, 1 lb bags)
Best default shock
Widely available calcium hypochlorite shock that raises chlorine fast without adding cyanuric acid — the right default for most pools.
Taylor
Reagent Refill Set
Taylor
Taylor Reagent Refill Set
Best kit refresh
Fresh reagents for your Taylor kit — because expired reagents read wrong, not just weak.
In The Swim
pH Reducer
In The Swim
In The Swim pH Reducer (Sodium Bisulfate, 30 lb)
Lower pH
Dry acid granules to bring high pH and alkalinity down — safer to handle than liquid muriatic acid.
In The Swim
Alkalinity Increaser
In The Swim
In The Swim Alkalinity Increaser (Sodium Bicarbonate, 25 lb)
Raise alkalinity
Pure sodium bicarbonate to raise total alkalinity — the buffer that keeps your pH from bouncing around.
Frequently asked questions
What’s the difference between pH Increaser and Alkalinity Increaser?
pH Increaser is soda ash (sodium carbonate) and mainly moves pH; Alkalinity Increaser is baking soda (sodium bicarbonate) and mainly moves total alkalinity. They overlap a little, but balance alkalinity first, then fine-tune pH.
How much do I add?
Start with about 6 ounces per 10,000 gallons, run the pump, wait a few hours, and retest. pH is easy to overshoot, so go gradually rather than dumping a large dose at once.
Is this the same as generic soda ash?
Chemically, yes — it’s 100% sodium carbonate. You’re paying for purity and convenient packaging, so it’s reasonable to buy on price among reputable brands.
Will it cloud my water?
It can temporarily if over-dosed or added too fast. Broadcast it slowly around the deep end with the pump running, and any brief cloudiness usually clears as it dissolves and circulates.
Can I use it in a saltwater pool?
Yes — soda ash works in all pool types. Salt pools often drift high in pH over time, so you may actually reach for pH Reducer more often than Increaser.
Why did my pH drop in the first place?
Common causes are heavy rain, acidic fill water, adding too much acid, or high bather load. Fixing alkalinity to the ideal 80–120 ppm range makes pH far more stable and reduces how often you need to correct it.