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Skim&Soak

Testing & Chemistry

How to Balance Pool Water

Four readings, corrected in one specific order, with the dose worked out for your volume rather than somebody else's.

By Scooter M.Last reviewed September 2, 2026How we work the numbers out
Calm, balanced swimming pool water reflecting the sky

We have not handled these products and we do not pretend to have. Here is what we did instead. Links to Amazon earn us a commission at no extra cost to you, and commission never decides a pick — disclosure.

How to Balance Pool Water - ranked
#ProductBest forThe spec it turns onPrice
1
Pool Mate Premium Alkalinity Increaser, 10 lb
Pool Mate Premium Alkalinity Increaser, 10 lbTop pick100% sodium bicarbonate and it says so, which is the only claim that lets you compute the dose yourself.
Raising total alkalinityListing states 100% sodium bicarbonate
Check price#ad
2
HTH Pool Care pH Down, 5 lb
HTH Pool Care pH Down, 5 lbSodium bisulfate with the maker's own target range and timing published, which is more guidance than most balancers give.
Lowering pHSodium bisulfate; HTH states a 7.2-7.6 target and a 4-6 hour wait after shocking
Check price#ad
3
In The Swim Pool Stabilizer, 100% Cyanuric Acid, 25 lb
In The Swim Pool Stabilizer, 100% Cyanuric Acid, 25 lb100% cyanuric acid at a purity that lets you compute the dose, for pools whose chlorine source does not supply its own.
Stabilizing a liquid-chlorine or salt pool100% cyanuric acid, granular
Check price#ad
4
Taylor Technologies K-1004 DPD 6-in-1 Pool Test Kit
Taylor Technologies K-1004 DPD 6-in-1 Pool Test KitIncludes an acid demand test, which is the only honest way to know how much pH reducer your pool needs.
The acid demand testDPD kit including acid and base demand titrations
Check price#ad
5
ARM & HAMMER Clear Balance pH Maintenance Tablets, 24 count
ARM & HAMMER Clear Balance pH Maintenance Tablets, 24 countThe skip. pH and alkalinity move in different directions for different reasons, and one tablet cannot correct both.
Nothing we would recommend it forDissolving tablets marketed as one-step pH and alkalinity maintenance
Check price#ad

First, know your volume

Every dose on this site is per gallon, so a wrong volume makes every subsequent number wrong by the same proportion. It takes five minutes with a tape measure.

Step 1: total alkalinity

Target 80 to 120 ppm, per HTH's own Alkalinity Up product page. Alkalinity is a buffer: it resists changes in pH. Low alkalinity is why a pool's pH bounces around and will not stay where you put it, so this correction has to come first or you will make the pH correction twice.

Alkalinity increaser is sodium bicarbonate. Every brand sells the same compound, and the only thing worth checking is whether the label admits 100% purity - because that is what lets you compute the dose.

Sodium bicarbonate to raise total alkalinity by 10 ppm
Pool volumeHow much
5,000 gal11 oz
10,000 gal1.4 lb
15,000 gal2.1 lb
20,000 gal2.8 lb
25,000 gal3.5 lb
30,000 gal4.2 lb
Where these come from: g of sodium bicarbonate = ((liters x ppm) / 1000) / 50.04 g per CaCO3 equivalent x 84.007 g per mole. For 15,000 gallons that is 15,000 gal = 56,781 L; ((56,781 x 10) / 1000) / 50.04 x 84.007 = 953 g = 2.1 lb. HTH advises adding with the pump running and retesting after six to eight hours of circulation. Do not stack two corrections before retesting. How we work these out.

Step 2: pH

Target 7.2 to 7.6, per HTH's pH Down product page. High pH blunts chlorine and clouds water; low pH corrodes surfaces, dissolves metal from heaters and irritates skin.

Two practical rules from HTH's own page: broadcast dry acid over the deep end with the pump running and do not pre-dissolve it, and wait four to six hours after shocking before adding acid so the two do not fight each other.

Step 3: cyanuric acid

HTH's stabilizer page gives the targets: 30 to 50 ppm on trichlor and dichlor pools, 60 to 80 ppm on saltwater. It also states that stabilizer prevents up to 90% of chlorine loss to sunlight, which is why an unstabilized outdoor pool is a losing proposition.

100% cyanuric acid to raise CYA by 30 ppm
Pool volumeHow much
5,000 gal1.3 lb
10,000 gal2.5 lb
15,000 gal3.8 lb
20,000 gal5 lb
25,000 gal6.3 lb
30,000 gal7.5 lb
Where these come from: lb of cyanuric acid = (ppm x gallons x 8.345) / 1,000,000. For 15,000 gallons that is (30 x 15,000 x 8.345) / 1,000,000 = 3.76 lb. Add through the skimmer with the pump running and wait 24 to 48 hours before retesting - it dissolves slowly, and an early retest reads low and tempts a second dose you do not need. How we work these out.

Under-dose deliberately. Cyanuric acid does not leave the pool except by dilution, so too much is a mistake you fix by draining water. Too little is a mistake you fix by adding more. See cyanuric acid.

Step 4: chlorine

Last, because how much you need depends on the three readings above. HTH states that one 3 inch tablet per 10,000 gallons per week holds free chlorine at 1 to 4 ppm, which is the routine sanitizing case.

For a correction or a shock, the dose tables and the arithmetic are on best pool shock. The ceiling is whatever your product's label states; Michigan's guidance notes that many pool chlorine products carry an NSF-listed maximum application rate of 10 ppm.

Calcium hardness, and why it is last

Roughly 200 to 400 ppm is the range generally worked to. We could not source that figure from a manufacturer's own page, so it is stated here as general industry practice rather than as a cited target - which is a distinction worth making, since everything else on this page has a source.

Low calcium is corrosive and pulls minerals out of plaster and grout. High calcium scales and clouds. It changes very slowly, so it is a seasonal check rather than a weekly one, and the only way down is dilution.

The picks

Pool Mate Premium Alkalinity Increaser, 10 lb

Top pick - Raising total alkalinity

Pool Mate Premium Alkalinity Increaser, 10 lb

100% sodium bicarbonate and it says so, which is the only claim that lets you compute the dose yourself.

The published figure

Listing states 100% sodium bicarbonate

Alkalinity increaser is sodium bicarbonate. Every brand sells the same compound, and the only thing worth checking is whether the label admits it.

Because this one states 100% purity, the arithmetic below applies exactly: 1.4 lb raises 10,000 gallons by 10 ppm.

Raise alkalinity before pH. Alkalinity is what stops pH bouncing, so correcting pH first means correcting it again.

What it does well

  • States 100% purity, so the dose is computable
  • Sold in a size that matches a real correction
  • Cheapest per ppm of the balancers here

What it costs you

  • Raises pH slightly as a side effect
  • Needs a full circulation cycle before retesting

Skip it if your alkalinity is already above 120 ppm — you need acid, not bicarbonate.

Check price on Amazon

#ad · how this is funded

HTH Pool Care pH Down, 5 lb

Pick 2 - Lowering pH

HTH Pool Care pH Down, 5 lb

Sodium bisulfate with the maker's own target range and timing published, which is more guidance than most balancers give.

The published figure

Sodium bisulfate; HTH states a 7.2-7.6 target and a 4-6 hour wait after shocking

HTH's page states the target range as 7.2 to 7.6 and tells you to wait four to six hours after shocking before adding it. Both are the kind of instruction people get wrong and no label usually gives.

How much you need depends on your total alkalinity, not on a chart. That is what an acid demand test measures, and why we recommend a kit that includes one.

Broadcast over the deep end with the pump running, and do not pre-dissolve — that instruction is on the label for a reason.

What it does well

  • Maker publishes the target range and the post-shock wait
  • Dry acid is far safer to store and handle than muriatic
  • Stated safe for vinyl, fiberglass, concrete and saltwater

What it costs you

  • Adds sulfate, which accumulates over many seasons
  • Dose depends on your alkalinity, so it needs an acid demand test

Skip it if your pH is high because your alkalinity is high. Fix the alkalinity and the pH usually follows.

Check price on Amazon

#ad · how this is funded

In The Swim Pool Stabilizer, 100% Cyanuric Acid, 25 lb

Pick 3 - Stabilizing a liquid-chlorine or salt pool

In The Swim Pool Stabilizer, 100% Cyanuric Acid, 25 lb

100% cyanuric acid at a purity that lets you compute the dose, for pools whose chlorine source does not supply its own.

The published figure

100% cyanuric acid, granular

Trichlor tablets and dichlor shock both add cyanuric acid as they dissolve. Liquid chlorine, cal-hypo and salt systems do not, so those pools need it added deliberately.

At 100% purity, 1 lb raises 10,000 gallons by 12 ppm. HTH's own stabilizer page states the useful targets: 30-50 ppm for trichlor and dichlor pools, 60-80 ppm for saltwater.

Cyanuric acid does not leave except by dilution. Adding too much is a mistake you fix by draining water, so under-dose and retest.

What it does well

  • 100% purity means the arithmetic is exact
  • Protects chlorine from UV loss, which HTH puts at up to 90%
  • One correction lasts until you dilute the water

What it costs you

  • Dissolves very slowly — 24 to 48 hours before a retest means anything
  • Cannot be removed except by draining and refilling

Skip it if you sanitize with trichlor tablets. Those already add stabilizer, and your problem is more likely too much of it.

Check price on Amazon

#ad · how this is funded

Taylor Technologies K-1004 DPD 6-in-1 Pool Test Kit

Pick 4 - The acid demand test

Taylor Technologies K-1004 DPD 6-in-1 Pool Test Kit

Includes an acid demand test, which is the only honest way to know how much pH reducer your pool needs.

The published figure

DPD kit including acid and base demand titrations

How much acid a pool needs to move pH from 8.0 to 7.5 depends on its total alkalinity, and no chart can tell you without knowing it. An acid demand test measures it directly.

That is why this site does not print a pH-down dose table: the number is a property of your water, not of the product, and the test costs a few dollars.

Six parameters rather than nine, so it does not cover cyanuric acid or salt.

What it does well

  • Acid and base demand titrations, which most kits omit
  • Cheaper than the nine-parameter kits

What it costs you

  • No cyanuric acid test
  • No salt test

Skip it if you need a cyanuric acid reading — that is a common problem this kit cannot see.

Check price on Amazon

#ad · how this is funded

ARM & HAMMER Clear Balance pH Maintenance Tablets, 24 count

Pick 5 - Nothing we would recommend it for

ARM & HAMMER Clear Balance pH Maintenance Tablets, 24 count

The skip. pH and alkalinity move in different directions for different reasons, and one tablet cannot correct both.

The published figure

Dissolving tablets marketed as one-step pH and alkalinity maintenance

Alkalinity is a buffer and pH is a reading. Raising alkalinity nudges pH up; lowering pH pulls alkalinity down. They are coupled, which is exactly why they need separate corrections.

A maintenance tablet can hold a pool that is already balanced. It cannot correct one that is not, and the pools that buy it are usually the second kind.

Buy sodium bicarbonate and dry acid separately. Between them they cost less and they can actually reach a target.

What it does well

  • Convenient if the water is already in range
  • No measuring

What it costs you

  • Cannot correct an out-of-range pool in either direction
  • Obscures which parameter you actually moved

Skip it if your alkalinity or pH is currently out of range — which is the reason people go looking for this product.

Check price on Amazon

#ad · how this is funded

Questions people actually ask

What order do I add pool chemicals in?
Total alkalinity, then pH, then cyanuric acid, then chlorine. Alkalinity is the buffer that holds pH steady, so correcting pH on a pool with low alkalinity means correcting it again within days. Never stack two corrections before retesting.
How do I calculate my pool volume?
For a rectangle: length times width times average depth times 7.48. For a round pool: 3.14 times radius squared times average depth times 7.48. Average depth means adding the shallow and deep figures and halving them.
How much baking soda do I need to raise alkalinity?
About 1.4 lb of sodium bicarbonate raises total alkalinity by 10 ppm in 10,000 gallons - and that figure is a calculation rather than a rule of thumb. The full working is shown above, and it scales directly with your own volume.
How much acid do I need to lower pool pH?
It depends on your total alkalinity, not just your volume, which is why no honest general table exists. Use a kit with an acid demand test - Taylor's K-1004 includes one - and dose to what it tells you.
How long should I wait between adding pool chemicals?
Let each addition circulate before adding the next. HTH advises six to eight hours of circulation before retesting alkalinity, four to six hours after shocking before adding acid, and 24 to 48 hours for cyanuric acid to dissolve fully.

Sources

Every figure on this page traces to one of these. Where a number could not be sourced, the page says so rather than estimating.

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