Pool Chemistry Calculator
Enter your latest water test to check your balance (LSI) and get a chlorine dose estimate. Free, no sign-up, built by the team behind ProHelper, the pool service software that runs your whole route, from chemistry to invoicing, in one app.
Your water test
Water balance (LSI)
0.45scaling· risk of scale on surfaces & equipment
Chlorine to add
Add about 24 fl oz (~3 cups) of 12.5% liquid chlorine to reach a target FC of 2.5 ppm.
Ideal 7.4–7.6 ppm
Ideal 60–120 ppm
Ideal 30–50 ppm
Ideal 200–400 ppm
This is the free preview of ProHelper's chemistry engine.
The full version auto-calculates exact doses per pool, adjusts for SWG/Stenner/tablets, applies heat-wave events, and logs every reading to the customer's history, offline, right at the pad.
Estimates for guidance only. Always follow product label instructions and retest after dosing.
Pool chemistry, explained
The LSI is a measure of whether your pool water is balanced, corrosive, or scale-forming. It combines pH, temperature, calcium hardness, and total alkalinity into one number. A value between −0.3 and +0.3 is considered balanced. Below that, water can etch plaster and corrode equipment; above it, scale can form on surfaces and heaters.
This tool estimates how much liquid chlorine to add to reach a target free-chlorine level based on your pool volume, current FC, and CYA. It is a guideline: always follow the product label, add chemicals safely, and retest before swimming.
Cyanuric acid (stabilizer) protects chlorine from sunlight but also reduces its effectiveness. The higher your CYA, the more free chlorine you need to keep the water sanitary, which is why the target FC range scales with your CYA level.
This is a free, simplified preview. ProHelper’s in-app chemistry engine goes much further: exact dosing per pool, support for salt systems, Stenner pumps and tablets, automatic adjustments for heat waves and high-use holidays, and a full reading history saved to each customer, all available offline in the field.
Run chemistry on every pool, automatically
ProHelper logs readings, calculates exact doses, and bills the route for you. Start free for 30 days.
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