Pool Water Adjustment Planner
Estimate free-chlorine demand and alkalinity adjustment without guessing a product or pH dose.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
This planner estimates additional available chlorine by mass and sodium bicarbonate from pool volume and ppm change; it does not calculate how much retail chlorine product to add. pH gives a direction, not an acid/base dose. Follow product labels, use appropriate protective equipment and ventilation, and never mix pool chemicals.
Worked example
calculated with the default values below
Pool volume 15,000 gal · Current free chlorine 0.5 ppm · Target free chlorine 3 ppm · Current pH 7.8 · Target pH 7.4 · Current total alkalinity 60 ppm · Target total alkalinity 100 ppm Additional available chlorine (theoretical) 142.0 g · pH adjustment direction pH needs lowering; use a product label and retest · Sodium bicarbonate estimate 9.00 lb · Safety and dosing note These are planning estimates, not product doses. Follow labels, never mix chemicals, circulate and retest.
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
Cl_g = max(0, Cl_t − Cl) × G × 3.785411784 ÷ 1000; A_lb = max(0, A_t − A) × 0.15 × G ÷ 10000
- Cl_g
- Additional available chlorine (g)
- Cl_t
- Target chlorine (ppm)
- Cl
- Current chlorine (ppm)
- G
- Pool volume (US gal)
- A_lb
- Sodium bicarbonate estimate (lb)
- A_t
- Target alkalinity (ppm)
- A
- Current alkalinity (ppm)
Chlorine is theoretical available-chlorine mass, not a product dose. Bicarbonate is an approximate alkalinity adjustment. pH direction is shown without an acid/base dose; follow labels and retest.
Frequently asked questions
Why is there no product or pH dose?
The chlorine result is only the theoretical additional mass of available chlorine; product strength determines the dose. The bicarbonate estimate uses 1.5 lb per 10,000 US gallons for a 10 ppm alkalinity rise. pH alone cannot determine an acid or base dose. Follow labels and retest.