Aquarium Dosing Calculator
Calculate exact dosages for aquarium fertilizers, medications, and water conditioners. Free dosing calculator with product reference table for all popular brands.
Dosing Instructions
For a 20-gallon tank, dose 0.40 mL of Seachem Prime. Add during water changes or to detoxify ammonia/nitrite.
All Dosing Products Reference
| Product | Category | Dose / Gallon | Unit | Your Dose (20 gal) | Instructions |
|---|---|---|---|---|---|
| Seachem Prime | conditioner | 0.02 | mL | 0.40 mL | Add during water changes or to detoxify ammonia/nitrite |
| Seachem Flourish | fertilizer | 0.02 | mL | 0.40 mL | Dose 1-2x per week for planted tanks |
| Seachem Excel | carbon | 0.04 | mL | 0.80 mL | Daily liquid carbon source for planted tanks |
| API Stress Coat | conditioner | 0.04 | mL | 0.80 mL | Use during water changes and when adding new fish |
| Ich-X | medication | 0.04 | mL | 0.80 mL | Dose every 24 hours until spots disappear + 3 days |
| API General Cure | medication | 0.04 | packet per 10gal | 0.80 packet per 10gal | Dose every 48 hours for 2 treatments |
| Fritz Maracyn | medication | 0.04 | packet per 10gal | 0.80 packet per 10gal | Dose daily for 5 days |
| Seachem Stability | bacteria | 0.02 | mL | 0.40 mL | Use for 7 days when cycling or after water changes |
How It Works
This calculator multiplies your tank volume by each product's recommended dose-per-gallon ratio to give you the exact amount to add. The formula is simple: Dose = Tank Volume (gallons) × Dose Per Gallon.
Select your tank size and choose a product from the dropdown. The calculator shows the precise dosage amount along with usage instructions from the manufacturer.
The reference table below shows dosages for all supported products at your tank size, making it easy to compare and plan your maintenance routine. Each product links to its Amazon listing for easy purchasing.
Always verify dosing instructions on your specific product's label, as formulations can change between product versions.
Frequently Asked Questions
Why is accurate dosing important for my aquarium?
Overdosing medications can harm fish, invertebrates, and beneficial bacteria. Underdosing may fail to treat infections or leave nutrient deficiencies in planted tanks. Accurate dosing based on your actual tank volume ensures treatments are effective without causing unnecessary stress.
Should I dose based on total tank volume or actual water volume?
For most products, dose based on actual water volume rather than the tank's rated size. A tank rated at 20 gallons typically holds about 16-18 gallons of water after accounting for substrate, decorations, and equipment. When in doubt, slightly underdosing is safer than overdosing.
How do I measure small doses accurately?
Use a graduated syringe (available at pharmacies) for doses under 5 mL. For doses under 1 mL, a dropper with mL markings works well. Many aquarium products include caps with measurement lines. Never eyeball doses for medications — precision matters.
Can I mix different aquarium medications together?
Generally, you should not mix medications unless the manufacturer specifically states they are compatible. Combining treatments can cause dangerous chemical reactions or amplify toxicity. Complete one treatment course, perform a water change, then begin the next treatment if needed.