Seachem Prime in an Ammonia or Nitrite Emergency

What the manufacturer says

Seachem specifies a normal dose of 5 mL per 200 litres of new water, with 50 US gallons given as the rounded gallon equivalent. Its directions distinguish treating replacement water from adding Prime directly to the aquarium, where the dose is based on aquarium volume.

The product FAQ permits up to five times the normal dose when ammonia or nitrite is above 2 ppm. This is an upper allowance, not an instruction to use the maximum for every detectable reading. Seachem says Prime does not physically remove those compounds; follow up with testing and correction of the underlying problem.

Do not postpone corrective action for a countdown

The earlier advice to wait 24 hours and to restrict all emergencies to 20% daily changes has been removed. Choose corrective action according to the measured problem, replacement-water conditions and the animals’ condition. If the cause or test result is uncertain, seek help from a fish-health professional or the manufacturer promptly.

A water change dilutes a dissolved substance when the replacement water contains less of it. For example, replacing half of well-mixed water containing 2 mg/L with water containing none leaves approximately 1 mg/L before further waste is produced. A 20% change under the same assumptions leaves 1.6 mg/L. These are dilution examples, not a universal water-change prescription.

Check the replacement water too. Chlorine treatment, temperature and major differences in water chemistry need to be addressed; adding untreated water can introduce a separate problem. Record what was changed and retest rather than assuming that dosing solved the cause.

Why an ammonia result may need interpretation

Seachem warns that Prime can interfere with some ammonia tests. Nessler-based tests are unsuitable in this situation; salicylate results need careful handling according to its FAQ. A total-ammonia result is not the same measurement as free ammonia. The former article’s claim that a green test can simply be ignored has been removed.

Record the test’s name, reading, dosing time and any water changes. A result that appears inconsistent is a reason to check the testing method, not proof that the animals are protected.

Oxygen and combining products

Seachem’s overdose guidance warns that sufficiently high doses can reduce oxygen. Low oxygen, heat, heavy stocking, poor circulation and other oxygen-reducing products can increase the risk. Maintain effective circulation and aeration. Do not interpret breathing distress as an automatic instruction to add more conditioner.

Prime plus eSHa is not a default emergency recipe. eSHa warns about conditioners and other treatments affecting its products. Check both products’ directions or obtain manufacturer advice for the exact combination. Removing chlorine safely and checking medication compatibility are both necessary.

What our two Prime tools actually calculate

• Dedicated Prime calculator: you enter net water volume and choose a multiplier from 1× to 5×. It does not accept an ammonia reading or choose a multiplier from a test result.
• Main calculator’s “Prime (Emergency Detox)” entry: this is a fixed 5× calculation. Selecting it is not a diagnosis or a recommendation to use that amount.

The tools retain their existing arithmetic. Both tools scale 5 mL per 200 litres. The dedicated tool uses 3.785 litres per US gallon and displays one decimal place; the main calculator uses 3.78541 and different display-rounding rules. Consequently, displayed amounts can differ. Always compare the applicable bottle directions and read how doses and rounding are calculated.

Sources and corrections

• Seachem Prime: directions and FAQs
• Seachem: overdose and oxygen precautions
• eSHa: general compatibility and water-conditioner guidance

The previous unsupported dose ladder, detailed chemical mechanism, guaranteed protection language and blanket water-change rules have been removed. This page summarises guidance and calculation limits; it does not present an independent efficacy trial.