Aquarium salt mix calculator

For a new batch, multiply final batch liters by the product’s grams-per-liter direction, then scale for the target salinity relative to the label reference. For an existing-system correction, the calculator first determines the salinity required in a separately mixed replacement batch, then scales the product ratio to that batch volume and salinity.

The proportional step is an estimate. Manufacturer tables, preparation temperature, final-volume instructions, batch variation, and measurement error can make real mixing behavior differ, so the finished water must be measured.

Some directions describe grams added to a starting water volume; others describe bringing the dissolved solution to a final volume. Those are not identical because dissolving salt changes volume. Follow the wording on the product label.

When the label defines a final volume, start with slightly less water, dissolve the weighed salt as directed, then bring the prepared solution to final volume after it reaches the specified temperature.

Dry-cup volume depends on crystal size, settling, humidity, and how the cup is filled. Two products can occupy the same cup volume but have different mass and produce different salinity.

Use a scale suitable for the batch size. If a label supplies cups only, follow that product direction and verify the batch; do not reuse the cup factor for another brand.

Use a clean, non-toxic container and add salt mix to the prepared water as directed by the manufacturer. Adding water onto a pile of salt can create a briefly concentrated solution and promote precipitation in some products.

Follow the product’s mixing time, temperature, circulation, and aeration directions. Once dissolved and conditioned, check salinity with a calibrated seawater-appropriate instrument and adjust the batch in small steps.

The correction mode uses an ideal mixing balance: water removed from the system is assumed to have the current salinity, and the measured replacement batch is assumed to mix evenly. If the selected replacement percentage would require salinity above the calculator’s supported range, it asks for a larger or staged plan instead of presenting an extreme batch.

Never pour the calculated dry mass into an aquarium containing animals. Confirm the measurement and calibration, prepare and measure the replacement water separately, and use a correction schedule appropriate to the species and system.