Aquarium Dosing Calculator
Calculate liquid aquarium additives by scaling the manufacturer's directions to your water volume. Entering the correct water volume and label ratio ensures you add the intended amount, while following product handling instructions protects your aquarium.Calculate liquid aquarium additives by scaling the manufacturer's directions to your water volume. Entering the correct water volume and label ratio ensures you add the intended amount, while following product handling instructions protects your aquarium.[1][2]
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How is the result calculated?
The calculation divides the water volume by the reference volume on the bottle, then multiplies that figure by the label amount. Always keep your volume units consistent before running the numbers.The calculation divides the water volume by the reference volume on the bottle, then multiplies that figure by the label amount. Always keep your volume units consistent before running the numbers.
For example, a label ratio of 1 mL per 10 L treats a 75 L aquarium by dividing 75 L by 10 L and multiplying by 1 mL, which equals 7.5 mL. This worked example illustrates the arithmetic, so always substitute your product's actual ratio.For example, a label ratio of 1 mL per 2.6 gal treats a 19.8 gal aquarium by dividing 19.8 gal by 2.6 gal and multiplying by 1 mL, which equals 7.5 mL. This worked example illustrates the arithmetic, so always substitute your product's actual ratio.
When a label specifies a US liquid volume unit, multiply that reference volume by 3.785 to convert it to litres before calculating. Carefully verify both the number and the unit, because copying an unadjusted label figure produces an incorrect dose.When a label specifies a US liquid volume unit, multiply that reference volume by 3.785 to convert it to litres before calculating. Carefully verify both the number and the unit, because copying an unadjusted label figure produces an incorrect dose.
Should I dose new water or the whole aquarium?
Always follow the specific instructions on the bottle. Seachem Prime directions differentiate between preparing replacement water and dosing directly into the aquarium, where the dose scales to total tank volume. Choose your input volume intentionally based on which method you are using.Always follow the specific instructions on the bottle. Seachem Prime directions differentiate between preparing replacement water and dosing directly into the aquarium, where the dose scales to total tank volume. Choose your input volume intentionally based on which method you are using.[3]
Never assume all water conditioners use identical procedures, even when products serve a similar purpose. Always enter the specific volume demanded by your chosen product's instructions.Never assume all water conditioners use identical procedures, even when products serve a similar purpose. Always enter the specific volume demanded by your chosen product's instructions.[3][1]
How do I measure aquarium additives accurately?
Use a clearly graduated measuring tool sized appropriately for your liquid dose, and follow all safety and handling guidelines printed on the bottle. Prepare new water with necessary treatments before adding it to the display.Use a clearly graduated measuring tool sized appropriately for your liquid dose, and follow all safety and handling guidelines printed on the bottle. Prepare new water with necessary treatments before adding it to the display.[1][2]
Maintain a written log of every additive used. Some treatments alter ammonia test results or interact with biological filtration, so tracking past doses helps you diagnose unexpected test outcomes.Maintain a written log of every additive used. Some treatments alter ammonia test results or interact with biological filtration, so tracking past doses helps you diagnose unexpected test outcomes.[1][2]
Questions
How do I calculate a dose for a smaller aquarium?
Divide your aquarium volume by the reference volume printed on the label, then multiply by the directed amount. A label ratio of 1 mL per 10 L gives 7.5 mL for 75 L of water.Divide your aquarium volume by the reference volume printed on the label, then multiply by the directed amount. A label ratio of 1 mL per 2.6 gal gives 7.5 mL for 19.8 gal of water.
Can a dosing calculator choose a fish medicine?
No. A calculator only scales numerical liquid amounts for a given water volume. Always select treatments by following the product's specific instructions and seeking appropriate fish-health advice before administering any remedy.No. A calculator only scales numerical liquid amounts for a given water volume. Always select treatments by following the product's specific instructions and seeking appropriate fish-health advice before administering any remedy.[2]
How do I check the result before using it?
Check the entered value and the unit together against the product label. Make sure both your tank volume and reference volume share the same measurement unit before dosing.Check the entered value and the unit together against the product label. Make sure both your tank volume and reference volume share the same measurement unit before dosing.
Can I use the tank size printed on the box?
Use the water volume relevant to the specific product instructions. Some treatments require dosing only the replacement water volume, while others scale to total aquarium capacity.Use the water volume relevant to the specific product instructions. Some treatments require dosing only the replacement water volume, while others scale to total aquarium capacity.[3][1]
Sources
- Choosing an aquarium — RSPCA. Accessed 2026-10-05.
- Ammonia in Aquatic Systems — UF/IFAS Extension. Accessed 2026-10-05.
- Seachem - Prime — Seachem. Accessed 2026-10-05.
Written from the sources above. Not yet reviewed by an aquarist.