Free Tool
Check your water balance with the Langelier Saturation Index (LSI), then get the exact chemical doses to hit your target readings — scaled to your pool's volume. Estimates: add slowly and retest.
Check water balance (LSI) and get chemical dosing to hit your targets
Balanced is −0.3 to +0.3. Below −0.3 the water is corrosive; above +0.3 it scales. Alkalinity is corrected for CYA (~0.32 × CYA).
Pool volume
Readings — current / target
Rule-of-thumb rates scaled to volume (per 10,000 gal). pH is buffered by alkalinity — treat pH doses as a starting point and retest before adding more.
Enter your test-kit readings and see whether the water is balanced, corrosive, or scaling — plus exactly how much of each chemical to add to fix it.
Run the LSI and dosing at the poolside from your phone and log it into a job. In ServicePros Hub the chemical list drops straight into a proposal or invoice.
Two questions matter for pool water: is it balanced, and how much do I add to fix it? This tool answers both.
Balance uses the Langelier Saturation Index: LSI = pH + temperature factor + calcium factor + alkalinity factor − a TDS constant. Between −0.3 and +0.3 the water is balanced; below that it's corrosive (etches plaster, corrodes metal), above it scales. Alkalinity is corrected for your CYA (stabilizer), which otherwise overstates the buffering.
Dosing scales standard rule-of-thumb rates to your pool volume (per 10,000 gallons). Enter current vs. target for chlorine, pH, alkalinity, calcium, and CYA and it returns amounts of liquid chlorine, muriatic acid, baking soda, soda ash, calcium chloride, and stabilizer. These are starting points — add chemicals slowly, circulate, and retest before adding more.
Aim for an LSI between −0.3 and +0.3, ideally near zero. Below −0.3 the water is corrosive and can etch plaster and corrode equipment; above +0.3 it tends to scale and cloud. The calculator flags which zone you're in.
To raise free chlorine, about 10.7 fluid ounces of 12.5% liquid chlorine per 1 ppm per 10,000 gallons is a common rule of thumb. Enter your current and target FC and pool volume and the calculator gives the amount.
Muriatic acid lowers both pH and total alkalinity. To raise alkalinity use baking soda; to raise pH use soda ash. Because pH is buffered by alkalinity, adjust alkalinity first, then fine-tune pH and retest.
For a rectangular pool, volume (gallons) = length × width × average depth (all in feet) × 7.48. Enter the dimensions or a known volume in the dosing tab and the calculator scales all doses to it.
Cyanuric acid (stabilizer) contributes to your total alkalinity reading but doesn't buffer the same way carbonate does. Subtracting roughly 0.32 × CYA gives the carbonate alkalinity used in the LSI, so the balance number is accurate.
This calculator is one of the trade tools inside ServicePros Hub — proposals, scheduling, invoicing, and card payments for home-service pros. One flat price. No tiers, no add-ons.
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