Total alkalinity is the buffer that keeps pH stable. Low alkalinity causes pH to swing wildly (which destroys plaster, irritates swimmers, and burns through chlorine). High alkalinity makes pH hard to lower and can cause scaling on plaster and equipment. Getting alkalinity right is the most consistent way to make pool chemistry easy.
Total alkalinity is the buffer that keeps pH stable. Low alkalinity causes pH to swing wildly (which destroys plaster, irritates swimmers, and burns through chlorine). High alkalinity makes pH hard to lower and can cause scaling on plaster and equipment. Getting alkalinity right is the most consistent way to make pool chemistry easy.
This guide is the complete WETYR Pools reference on raising and maintaining alkalinity. We cover the target range (80 to 120 ppm), the dose math for sodium bicarbonate (baking soda), how alkalinity interacts with pH, and the common mistakes that drive alkalinity down.
If your pool has chronic alkalinity instability, request a chemistry diagnosis from WETYR Pools. Chronic low alkalinity usually has a root cause (acidic rainfall, low-alkalinity fill water, chlorine source acidity) that the right service program addresses. Use the form on this page or email [email protected].
Total alkalinity: 80 to 120 ppm is the standard range for residential pools. Pools with cyanuric acid (stabilized chlorine) can target 80 to 100 ppm. Salt pools target 80 to 120 ppm. Spas target 80 to 120 ppm. Below 80 ppm: pH gets unstable. Below 60 ppm: pH crashes occur unpredictably. Above 120 ppm: scaling and high-pH lockup.
Total alkalinity and pH interact. Raising alkalinity also slightly raises pH. Lowering pH slightly lowers alkalinity. Adjustments need to be sequenced: alkalinity first (it buffers), then pH. Trying to fix pH without first fixing alkalinity leads to constant chasing.
Tools: a reliable test kit (Taylor K-2006 reagent kit reads alkalinity accurately). Strips drift and read low; do not rely on strips for alkalinity. Test once a week minimum during the season.
Use a Taylor K-2006 or equivalent reagent kit. Strips are unreliable for alkalinity. Test by adding the specified drops to a measured water sample; count the drops until the indicator changes color. Each drop is typically 10 ppm of alkalinity. Record the result.
Sodium bicarbonate (baking soda) is the standard chemical to raise total alkalinity. Dose: 1.5 pounds per 10,000 gallons raises alkalinity by 10 ppm. To raise from 60 ppm to 100 ppm in a 20,000-gallon pool: 40 ppm gap x 1.5 pounds x 2 (for 20,000 gallons) = 12 pounds. Buy pool-grade alkalinity increaser or food-grade sodium bicarbonate (Arm and Hammer baking soda); they are the same chemical.
Before adding alkalinity increaser, test pH. If pH is 7.2 to 7.8, you are fine to add alkalinity in one dose. If pH is below 7.0 or above 7.8, raising alkalinity will exaggerate the issue. Split the alkalinity dose across two days and adjust pH separately between doses.
With the pump running, broadcast the sodium bicarbonate around the pool perimeter. For larger doses (over 8 pounds), split across two evenings. Pre-dissolve in a bucket of pool water if you have a vinyl liner pool (pile dissolving slowly can bleach the liner).
Let the sodium bicarbonate mix and dissolve fully before re-testing. Most fully dissolves in 4 to 6 hours of circulation.
After 6 to 8 hours of mixing, re-test alkalinity and pH. If alkalinity is in range (80 to 120 ppm) and pH is in range (7.4 to 7.6), you are done. If pH is high (above 7.8), lower it slowly with muriatic acid; this will also slightly lower alkalinity, so adjust in small increments and re-test.
Chronic low alkalinity has a cause. Common: acidic rain (rainwater is naturally pH 5.5 and dilutes alkalinity), trichlor chlorine tablets (trichlor is acidic), low-alkalinity fill water (test your tap water), heavy chlorine use (each pound of trichlor lowers alkalinity). Identify the cause and address it for stable chemistry.
Alkalinity is the most DIY-friendly pool chemistry adjustment. Sodium bicarbonate is safe, cheap, and forgiving (overdosing slightly is not catastrophic; you can let pH drift it down naturally). Most owners can maintain alkalinity in range with weekly testing and monthly adjustment.
Call a pro when alkalinity bounces wildly week to week (suggests an underlying instability), when you cannot get pH and alkalinity to stabilize together, when calcium hardness is also unstable (suggests fill water issue), or when you want a service to handle all chemistry on a schedule.
WETYR Pools provides chemistry testing and balancing as part of routine weekly service across our maintenance markets. Every visit includes test of pH, total alkalinity, calcium hardness, free chlorine, combined chlorine, and cyanuric acid, with adjustment to target. Owners receive a documented service log.
Cost for chemistry-included weekly service: $125 to $225 per month depending on pool size. Standalone chemistry visits (water test, recommendations, no balance): $50 to $100. Full balance with chemistry: $125 to $250 per visit.
Test weekly. Adjust monthly. Track readings over time so you see the trend. Switch from trichlor tablets to liquid chlorine or salt generation if trichlor is driving alkalinity down. Top off promptly after heavy rain to dilute the acidic rainwater impact.
If your fill water is low alkalinity (below 80 ppm), every top-off pulls pool alkalinity down. Monthly maintenance dose of sodium bicarbonate at 1 to 2 pounds per 10,000 gallons keeps the buffer steady. WETYR Pools' weekly service handles all of this automatically.
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20 of the most-asked questions on Reddit, Quora, and pool owner forums, answered by the WETYR Pools team.
Total alkalinity 80 to 120 ppm is the standard range. Pools with stabilized chlorine target 80 to 100 ppm. Below 80: pH unstable. Above 120: scaling risk and high-pH lockup.
1.5 pounds of sodium bicarbonate per 10,000 gallons raises total alkalinity by 10 ppm. To raise from 60 to 100 ppm in a 20,000-gallon pool: 12 pounds. Baking soda and pool-grade alkalinity increaser are the same chemical.
Yes. Food-grade sodium bicarbonate (Arm and Hammer) is the same chemical as pool-grade alkalinity increaser, usually at a fraction of the price per pound. Use the food-grade product confidently.
Yes, slightly. Sodium bicarbonate raises both alkalinity (significantly) and pH (slightly). For large alkalinity adjustments, the pH rise can be noticeable; re-test after and adjust pH separately if needed.
pH measures how acidic or basic the water is (target 7.4 to 7.6). Total alkalinity measures the water's ability to buffer pH against changes (target 80 to 120 ppm). Low alkalinity makes pH unstable. They are related but not the same; adjust alkalinity first, then pH.
Acidic rain, trichlor chlorine tablets (acidic), low-alkalinity fill water, heavy chlorine use, occasional muriatic acid additions to lower pH. Each of these pulls alkalinity down slowly over time.
Weekly during the swim season. Twice weekly for heavily used pools. Monthly during off-season (winter). A reagent test kit (Taylor K-2006) is the reliable tool; strips drift.
Yes; they do not interact. Add alkalinity first, run pump 4 to 6 hours, then add chlorine. Or add both with several hours between them. Order matters only if pH is out of range.
Add muriatic acid (or dry acid, sodium bisulfate). Each acid addition lowers both alkalinity and pH. Add in small doses (8 to 16 ounces muriatic per 10,000 gallons), wait, re-test. Lowering alkalinity below 120 ppm without crashing pH requires patience.
30 to 50 ppm for traditional chlorine pools. 60 to 80 ppm for salt pools. Above 80 ppm: chlorine effectiveness drops. Above 100 ppm: dilute the pool to bring CYA down.
Almost always low alkalinity. pH cannot stay stable when alkalinity is below 80 ppm. Raise alkalinity to 100 ppm first; pH will then hold.
Yes, after 4 to 6 hours of circulation and mixing. Baking soda is safe at the doses used in pools (much lower concentration than household cooking use).
Total alkalinity is the sum of all alkaline ions (mostly carbonate and bicarbonate). Carbonate alkalinity is specifically the carbonate fraction, relevant when cyanuric acid is high (CYA contributes to total alkalinity readings; adjusted alkalinity = total alkalinity minus 1/3 of CYA). For most pools, total alkalinity is the only number you need to track.
Sustained alkalinity over 180 to 200 ppm causes scaling on plaster, tile, and equipment. Plaster pools can develop calcium nodules. Heater heat exchangers scale up. Lower with acid; do not let it stay high.
Yes. WETYR Pools provides chemistry testing and balancing as part of weekly maintenance service. Includes alkalinity, pH, calcium hardness, chlorine, and cyanuric acid on every visit. Request through the form on this page or email [email protected].
Possible but not recommended. Broadcasting around the pool perimeter dissolves it more evenly. Adding to the skimmer concentrates it at the equipment pad; for sodium bicarbonate, that is not dangerous, but for other chemicals (especially acid), it can damage seals and equipment.
Materials: $5 to $30 depending on how much baking soda you need. Test kit: $80 to $120 one-time. Professional chemistry visit: $50 to $250. Weekly service: $125 to $225 per month including chemistry.
Yes, in severely low pH water or very heavily acidic water. Take action immediately: pH crash is imminent if not already happening. Add a strong dose of sodium bicarbonate (3 to 4 pounds per 10,000 gallons), pump 6 hours, re-test. May need a second dose.
Before. Balance alkalinity and pH first, then shock. Shock is much more effective at correct pH (7.2 to 7.6). Shocking before adjusting alkalinity wastes chlorine.
Washing soda is sodium carbonate, a different chemical that raises both pH and alkalinity strongly. Used to raise pH when alkalinity is already in range. Do not confuse with sodium bicarbonate (baking soda); the doses and effects are different.
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