Koi Pond Salt Calculator
Free Calculator
Calculate the amount of salt needed for a koi pond
Enter pond volume, measured current salinity, and the target concentration you have already chosen. The calculator determines how much pure sodium chloride would theoretically be required to make up the difference.
1. Pond volume
Include water in connected filters and chambers. Calculate pond volume.
2. Salinity change
Use a measured value when salt may already be present.
This tool does not choose a treatment level for you.
Theoretical pure salt required
Equivalent to 0 ppt or about 0 ppm.
Calculation assumes pure sodium chloride and water density near 1 kg/L. Commercial products, measurement uncertainty, displacement, and actual pond volume can change the concentration achieved.
Salt calculation formula
Metric
liters × concentration increase (%) ÷ 100 = kg salt
US gallons
gallons × concentration increase (%) × 0.08345 = lb salt
Unit conversion
0.1% = 1 ppt ≈ 1,000 ppm
The familiar rounded pond rule of roughly 1 pound per 100 US gallons for a 0.1% increase is intentionally approximate. Using the mass of water gives about 0.835 pounds per 100 US gallons for a theoretical 0.1% increase.
Important salt note
This calculator performs concentration math only. It does not diagnose fish disease, recommend a target concentration, or determine whether salt is compatible with a medication, pond plant, invertebrate, or treatment plan. Salt remains behind when water evaporates; it is reduced mainly when salted water is physically removed and replaced.