PoolChem Tracker

Pool Chemistry Explained

Total Alkalinity (TA)

Target range

Total alkalinity should sit between 60 and 90 ppm for most pools. Lower than 60 and pH starts swinging wildly with any chemical addition. Higher than 90 and pH drifts persistently upward, no matter how often you add acid.

Why TA matters: pH stability

TA's only real job is to buffer pH. Without it, your pH would swing several points every time you added chlorine, acid, or even rainwater. The buffer works in both directions:

• When acid is added, TA absorbs the hydrogen ions before they can drop pH. The TA itself decreases, but pH barely moves.
• When something tries to push pH up (CO₂ outgassing, soda ash, salt cells), the buffer resists that too.

Think of TA as the size of the brake pedal on your pH. A larger buffer (higher TA) means it takes more chemical to move pH at all — but once it does move, it tends to overshoot. A smaller buffer (lower TA) means pH responds quickly, but also unpredictably.

The pH and TA relationship

You can't manage one without managing the other. The way they interact is the source of most "I keep adding chemicals but nothing works" pool problems.

If your pH keeps rising no matter how much acid you add, the real problem is almost always high TA. Lowering pH only solves the symptom for a day or two; lowering TA solves the cause. See why pH keeps rising for the full diagnostic.

What raises TA

• Baking soda (sodium bicarbonate) — the standard chemical for raising TA. Roughly 1.5 lbs raises TA by about 10 ppm in 10,000 gallons. Has only a minimal effect on pH.
• Soda ash (sodium carbonate) — raises TA as a side effect of raising pH. Use when both pH and TA are low.
• Fill water — many municipal water sources are moderately alkaline. Topping off after evaporation slowly adds TA over the season.
• Cal-hypo shock — small TA increase per dose; rarely significant on its own.

What lowers TA

• Muriatic acid — lowers both pH and TA. The standard chemical for bringing TA down.
• Dry acid (sodium bisulfate) — same effect as muriatic acid, but adds sulfates to the water.
• Trichlor tablets — strongly acidic, gradually lowers TA along with pH over time.
• Heavy rain — dilutes TA temporarily. Significant in small pools after big storms.

Lowering high TA without crashing pH

Lowering TA is the most awkward adjustment in pool chemistry. Acid lowers both pH and TA — but pH bounces back faster than TA does. Adding all the acid at once crashes pH below 7.0 while TA only drops part-way to target.

The standard technique:

1. Add acid in stages, not all at once. Drop pH to about 7.0–7.2.
2. Aerate the water — run waterfalls, point return jets upward, or use a fountain. Aeration drives CO₂ off, which raises pH while leaving TA unchanged.
3. Wait, retest, repeat. Each cycle drops TA without dropping average pH. It may take days or weeks for high-TA pools to reach target.

See how to lower pool alkalinity for the full step-by-step.

How TA is measured

Test kits measure TA by drop-count titration. You add an indicator (usually bromcresol green/methyl red), then add a small acid reagent one drop at a time until the color changes from green to red. Each drop represents a fixed amount of TA (typically 10 ppm).

Test strips can read TA but are notoriously imprecise for this parameter — color pads in the alkalinity range are similar shades and easy to misread. A liquid kit (Taylor K-2006, TF-100, or similar) is much more reliable. See test strips vs liquid test kits for the full comparison.

The CYA correction

One subtlety: when cyanuric acid (CYA) is high, a standard TA test slightly overstates your real carbonate alkalinity. CYA itself contributes a small amount of "cyanurate alkalinity" to the titration reading without providing real pH buffering.

At CYA 60 ppm, your effective carbonate alkalinity is about 20 ppm lower than your test reading. This correction matters most when calculating LSI (water balance), but it also explains why pools with high CYA sometimes feel like their TA is "fighting" them harder than the number suggests. See LSI explained for how this factors into water balance.