Aquarium dosing calculator

The scale factor is actual treated water volume divided by the volume printed on the product label. Multiply the label amount by that factor. A label dose of 5 mL per 10 US gallons scales to 14.5 mL for 29 US gallons because 29 divided by 10 equals 2.9.

Both volumes are converted to liters internally before the ratio is calculated, so a label written in gallons can be scaled to an aquarium measured in liters without mixing incompatible units.

Advertised tank capacity can be higher than working water volume after substrate, hardscape, an air gap, internal equipment, or a sump operating level are considered. Read the product instructions carefully: some products are dosed for total system volume, some for replacement water, and some for the amount of new tap water being treated.

Do not automatically subtract a standard percentage. Measure or estimate the relevant water volume for the specific label direction, then keep that basis in your aquarium notes.

Dispenser output varies between products, replacement pump heads, partial presses, viscosity, and wear. Measure several complete pumps into a graduated syringe or cylinder, divide the total milliliters by the pump count, and enter that average.

Re-check pump output after moving product to another bottle or changing the dispenser. A saved value is only valid for that pump and product setup.

This calculator uses US customary definitions: one teaspoon is about 4.9289 mL and one tablespoon is about 14.7868 mL. Product labels sometimes round those values to 5 mL and 15 mL, so the label’s own milliliter value wins when both are printed.

Household spoons vary and are difficult to read accurately. Use a graduated syringe, pipette, cup, or scale appropriate to the amount whenever precision affects livestock safety.

Grams measure mass and milliliters measure volume. Converting between them requires product density in grams per milliliter. Water is close to 1 g/mL under ordinary conditions, but concentrated liquids and dry powders can be far above or below that value.

If a powder label gives a mass dose, scale it in grams and use a suitable scale. Do not convert it to spoons unless the manufacturer supplies a product-specific volume equivalence or density.

A mathematical result does not determine whether a medication is suitable, whether carbon or UV should be removed, how often it can be repeated, or whether sensitive fish, shrimp, snails, corals, plants, or biological filtration can tolerate it.

Follow the current manufacturer label, contraindications, maximum frequency, and aquatic-veterinary guidance. Re-check the decimal point and unit before adding any safety-critical dose.