Calculator Methodology
Skimmer's free calculators run the same math the app uses. This page documents where that math comes from and what it assumes, so you can check it rather than trust it blindly.
Dosing calculators (chlorine, pH, alkalinity, calcium, CYA, salt)
- Each dose is computed from your pool volume in gallons and the gap between your current reading and your target, using the standard treatment rates published in industry references and on the chemical products themselves (for example, the widely-used "parts per million per pound per 10,000 gallons" rates).
- Where a parameter can only practically be lowered by dilution (calcium hardness, cyanuric acid, salt), we show an honest drain-and-refill calculation rather than implying a chemical shortcut that does not exist.
- Results are a starting estimate. Real pools vary, so we recommend adding roughly three-quarters of a large correction, re-testing, and adjusting, rather than dosing to target in one shot.
The Langelier Saturation Index (LSI)
- The LSI calculator uses the standard formula LSI = pH + temperature factor + calcium hardness factor + alkalinity factor − 12.1, with the widely-published factor tables.
- We linearly interpolate between the nearest published table values rather than rounding to the closest one, which gives a smoother, more realistic number for readings that fall between entries.
- Balanced is −0.3 to +0.3. Below that, water tends to be corrosive; above it, scale-forming. Total dissolved solids is treated as optional advisory context, not a driver of the core number.
Volume estimates
The volume calculatoruses the standard geometric formulas for rectangle, round, oval, kidney, L-shape, Grecian and above-ground pools, with average, shallow and deep, or hopper depth. Irregular pools are an estimate; if you have the builder's spec, use that number instead.
Assumptions and limits
- We assume you have an accurate, recent water test. A calculator cannot fix a bad reading.
- Local water chemistry, product concentration, and pool surface can all shift the real answer. Follow the product label when it disagrees with a general rate.
- These tools do not replace a professional for equipment, electrical, or structural issues. See our editorial policy.