FishTankAquarium dosing calculator
How much water conditioner, medicine, bottled bacteria or plant fertilizer does your tank need? Pick the product, type in your tank size, and this free calculator scales the label dose for you in ml, teaspoons or drops. Or type in the dose from any label.
For water conditioners, enter the amount of new water you're adding. For medicines and fertilizer, enter the real water in the tank: about 10–15% less than the tank's size once gravel and decor are in. The volume calculator works it out. Always check the label on your bottle, because brands change their formulas.
Keep a record of your tank. Get my free printable tank log: 13 weeks of water tests, water changes and filter care, with healthy levels at a glance.
Send me the free logLabel doses at a glance
| Product | Label dose | How often |
|---|---|---|
| Seachem Prime | 5 ml per 50 gallons | Each water change, for the new water |
| API Stress Coat | 5 ml per 10 gallons | Each water change, for the new water |
| Seachem Stability (first day) | 5 ml per 10 gallons | Day 1 |
| Seachem Stability (daily, days 2–7) | 5 ml per 20 gallons | Once a day for 7 days |
| Dr. Tim's Ammonium Chloride (fishless cycling) | 4 drops per 1 gallon | To reach about 2 ppm ammonia |
| Ich-X | 5 ml per 10 gallons | Every 24 hours |
| Seachem ParaGuard | 5 ml per 10 gallons | Once a day |
| Seachem KanaPlex | 1 scoop per 5 gallons | Every 48 hours, up to 3 doses |
| Hikari PraziPro | 5 ml per 20 gallons | One dose, left for 5–7 days |
| API Aquarium Salt | 1 tbsp per 5 gallons | Once, then only for the water you replace |
| Seachem Flourish | 5 ml per 60 gallons | Once or twice a week |
| Seachem Flourish Excel (daily) | 5 ml per 50 gallons | Once a day |
1 US gallon is 3.785 liters. 1 teaspoon is about 5 ml, 1 tablespoon about 15 ml, and 1 ml is about 20 drops.
Dosing tips
- Dose for the water, not the tank label. A 20 gallon tank with gravel, rocks and wood often holds 17 gallons or less. Overdosing medicine is a bigger risk than a slight underdose.
- Pull carbon out of the filter while you treat, and put fresh carbon back in afterwards to clear the medicine.
- Add air. Many medicines lower oxygen, so add an air stone during treatment.
- One medicine at a time, unless the label says two can be combined.
- Shrimp, snails and scaleless fish (corydoras, loaches) are sensitive to salt, copper and some parasite medicines. Read the label first.
Dosing helpers
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- DosingPlastic dosing syringesMeasure ml exactly instead of guessing with the bottle cap.
- Water conditionerSeachem Prime (500 ml)The conditioner I dose with every water change.
- MeasuringMeasuring spoon setFor salt and powdered medicines. Keep a set just for the fish tank.
- Air pumpTetra Whisper air pump, 10–30 gallonsExtra oxygen while you treat with medicine.
Related: Fish symptom checker · Water test results tool · Aquarium volume calculator · Best water conditioners · CO2 and fertilizer