A little less guesswork.
Prime dosing calculator
Use the standard rate for replacement water or the full system, as applicable.
Read the emergency and test-limitations guide →
Clear amounts. Visible assumptions.
Your calculation, explained
Choose a product and enter the water you’re actually dosing.
- Check the exact product and formulation.
- Use measured water, or make an explicit estimate.
- Review the amount, source and any schedule.
Product guide · edited 28 October 2026
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Which water volume should I enter?
For water prepared separately, enter only the replacement water. When adding Prime directly to the aquarium, choose full-system mode and enter the aquarium water volume. The standard reference is 5 mL per 200 L.
Worked examples
These illustrations use 100 L of measured water, without a decor deduction. Choose the matching stage or formulation above for your own water volume. They do not select a treatment or establish livestock suitability.
New water prepared separately
| Stage | Amount or action for 100 L |
|---|---|
| With Water Changes | 2.5 mL |
Example only. Your calculation above uses your own inputs. Small amounts and powder fractions still need equipment that can measure them reliably.
Before you measure
Visual help: Read your bottle label · Read a small liquid scale. Teaching diagrams do not replace your bottle or measuring-device instructions.
Emergency, high-chloramine and temperature adjustments are outside this standard calculation. A test reading alone does not select a multiplier.
Product-specific checks from the calculation record
- For water prepared separately, enter the new water amount. When adding Prime directly to the aquarium, Seachem says to base the dose on the full aquarium volume.
- This calculator supports the normal dose only. Temperature-related, high-chloramine and emergency adjustments are not selected automatically.
Can I use the replacement-water result for direct addition?
Seachem specifies aquarium volume for direct addition. Change the mode and volume before measuring.
Sources and next steps
Seachem manufacturer directions →
Manufacturer page consulted 28 October 2026. Match the exact bottle and leaflet; editorial review does not establish diagnosis or compatibility.