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How the calculation works
Batch mode combines a lower-salinity source and a higher-salinity source to reach a target between them. It weights salinity by water mass, using EOS-80 density at the entered common reference temperature. This differs slightly from a simple volume-weighted average because saltier water is denser.
Replacement mode retains the unremoved tank water and solves for the new water’s salinity. Enter actual system volume, current and desired tank salinity, and the chosen change percentage. An impossible target that needs replacement outside 0–42 ppt produces an error. No livestock salinity target or acclimation speed is selected for you.
The model treats ppt as salt mass per solution mass and source volumes as additive planning quantities. Real mixing can change final volume slightly, and aquarium salinity measurements have uncertainty. Prepare replacement water separately, dissolve fully, equalize temperature and verify salinity with a calibrated instrument before use. SG output uses the same reference temperature for both density terms.
Worked example
To combine 20 liters of source water at 0 and 35 ppt toward 10 ppt at 25°C, use about 14.39 liters of the lower source and 5.61 liters of the higher source. This is measured water mixing, not a dry-salt gram recipe.
Common questions
Can I use table salt or a universal grams-per-liter dose?
This tool gives no dry-salt dose. Use the appropriate marine-salt product’s verified directions and a final salinity measurement; products and ionic composition differ.
Is batch target the same as tank target?
Only for a full replacement. During a partial change, retained tank water contributes salt. Use replacement mode to distinguish the two targets.