Calculate water salinity levels and salt requirements from conductivity, specific gravity, or PPT measurements for pools, aquariums, and marine applications.
Converted Salinity
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Parts Per Thousand (ppt)
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Specific Gravity
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Conductivity
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Salt Required
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The ideal salinity level for a saltwater pool is typically between 2,700-3,400 ppm (parts per million), which is equivalent to about 2.7-3.4 ppt. This is much lower than ocean water, which is around 35 ppt.
To convert specific gravity to ppt, use the formula: ppt = (Specific Gravity - 1) × 1000. For example, a specific gravity of 1.025 equals 25 ppt salinity.
Conductivity measures how well water conducts electricity (measured in mS/cm), while salinity measures the total amount of dissolved salts (measured in ppt or ppm). Higher salt content increases conductivity, so they're related but not identical measurements.
The amount of salt needed depends on your pool volume, current salinity level, and target salinity. Generally, you need about 8-10 pounds of salt per 1,000 gallons to increase salinity by 1,000 ppm.
Yes, temperature affects salinity measurements because it influences water density and conductivity. Most salinity meters automatically compensate for temperature, but manual calculations should account for temperature variations.
Ocean water typically has a salinity of about 35 ppt (35,000 ppm) or a specific gravity of 1.025. This is much higher than what's used in saltwater pools or most aquarium applications.
Test your saltwater pool's salinity at least once a week during swimming season. More frequent testing may be needed after heavy rainfall, adding fresh water, or if you notice changes in water quality.