System Volume Calculator

This calculator estimates the volume of water in an aquarium by noting the change in salinity that occurs when a known quantity of freshwater is added. To use it, first measure the salinity of your system. Then, add a known amount of RODI freshwater and let it mix thoroughly. After the water has mixed, test your salinity again.

To get a reasonable estimate from this calculator with a salinity measuring accuracy of 0.1ppt, you will need to add enough RODI water to cause around a 12% drop in salinity. If your salinity measuring accuracy is 0.01ppt, you will only need around a 2% drop in salinity ().

The accuracy of this calculator can always be increased by creating a larger salinity drop (up to 50%) and/or using a better salinity measuring device. However, keep in mind that too large of a drop in salinity will have a detrimental effect on your tank inhabitants.