Pool Salt Calculator
Pool Salt Calculator needed to reach target salt salinity in any pool from volume and ppm, with unit conversions and formulas.
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Helping Notes
Fields mirror the reference: Pool volume, Current salt concentration, Desired salt concentration. If current exceeds desired, tool gives water to replace instead of salt to add.
Typical acceptable salinity is 2700–3400 ppm, with 3200 ppm often ideal; always verify your system’s target level.
Results
Salt to Add
Water to Replace
Inputs Echo
What Is a Pool Salt Calculator?
A Pool Salt Calculator determines how much pure sodium chloride you must add to raise your pool’s salinity to a chosen target. Enter your pool volume and current salt level, pick a target range, and the tool computes the exact mass of salt to add. It supports both metric and US customary units, handles irregular pool shapes by converting volume from dimensions, and returns easy-to-use results for kilograms or pounds. Because salt systems (saltwater chlorine generators) require specific salinity bands for efficient operation, a precise addition prevents underperformance, error codes, or unnecessary dilution later. The calculator also provides reverse checks—predicting the new salinity if you add a known amount of salt—so you can plan bag counts and avoid overshooting.
About the Pool Salt Calculator
The computation rests on a simple concentration relationship: parts per million (ppm) are milligrams of solute per liter of water. The tool first computes the required increase Δppm = target − current (never below zero), then translates that increase into mass using pool volume. For US users who track gallons, it uses the standard water-weight constant to convert ppm to pounds directly. Geometry helpers convert dimensions into volume for rectangles and circles, and unit handlers standardize everything internally before output. You can also convert between ppm and percent salinity for controllers that display %; the calculator keeps both consistent. Finally, it can suggest bag counts from your selected bag size to simplify purchasing.
Increase needed: Δppm = max(0, ppmtarget − ppmcurrent)
Salt needed (kilograms): mkg = VL·Δppm / 106
Salt needed (pounds): mlb = Vgal · Δppm · 8.34×10⁻⁶
After adding mass m: ppmnew = ppmcurrent + (mkg/VL)·106
Volume from dimensions (rectangular, feet): Vgal = LftWftDavg,ft × 7.48052
Volume from dimensions (round, feet): Vgal = π·(Dft²/4)·Davg,ft × 7.48052
Percent ↔ ppm: ppm = 10⁴·% ; % = ppm/10⁴
Bags (size B): Nbags = m / B
How to Use This Pool Salt Calculator
- Measure current salinity (ppm) with a reliable test. Select your desired target (commonly within manufacturer’s recommended band).
- Enter pool volume directly or have the calculator compute it from shape and dimensions. Choose output units (kg or lb).
- Optionally enter bag size to see bag counts. Submit to view required salt and predicted new ppm after addition.
- Broadcast salt across the pool surface with the pump running, brush to help dissolve, and retest after full mixing.
Examples
- 15,000 gal from 1,500 → 3,000 ppm: Δppm = 1,500 ⇒ m ≈ 187.65 lb.
- 40,000 L from 0 → 3,000 ppm: m = 120 kg.
- 12,000 gal from 2,600 → 3,200 ppm: Δppm = 600 ⇒ m ≈ 60.05 lb.
- Add 25 kg to 30,000 L at 2,500 ppm: ppmnew ≈ 3,333.
Formula Snippets Ready for Rendering
FAQs
What salinity should my saltwater pool run at?
Most generators operate best around 2,700–3,400 ppm. Check your manufacturer’s recommended range and pick a target inside it.
What kind of salt should I buy?
Use high-purity pool salt (food-grade or solar-evaporated NaCl) without additives, anti-caking agents, rust inhibitors, or iodine.
Can I swim right after adding salt?
Yes, once salt has dissolved and circulated. Ensure chlorine and pH are within safe ranges before swimming.
Why did my control panel reading differ from my test kit?
Temperature, sensor calibration, and scaling methods vary. Recalibrate sensors periodically and confirm with a reliable drop test.
How do rain and splash-out affect salinity?
Rain and top-ups dilute salt; evaporation does not remove salt. Backwashing and splash-out reduce salt and may require re-dosing.
What if I overshoot the target ppm?
Dilute by partially draining and refilling with fresh water, then retest. Avoid chemical reducers claiming to remove salt.
How often should I add salt?
After the initial dose, only when tests show a drop—commonly after rain, backwash, or water replacement events.
Will high salinity damage equipment?
Moderate increases within spec are safe. Prolonged high ppm can stress heaters, stonework, and metals. Stay within manufacturer limits.
Where should I pour the salt?
Broadcast across the deep end with the pump running; brush to prevent piles on surfaces that could cause discoloration.
How long should I circulate after dosing?
Run the pump until fully dissolved and mixed—typically a full turnover cycle—then retest to verify the final ppm.
Can I use table salt?
Avoid iodized or anti-caking additives. Use pool salt or pure water-softener salt rated for pools to protect equipment.
How do I estimate bag counts?
Divide required mass by bag size. For example, 120 kg ÷ 20 kg bags = 6 bags.
How do I convert between percent and ppm?
Use 1% = 10,000 ppm. For example, 0.32% equals 3,200 ppm.