What is Prime for fish tanks?

Prime is a concentrated water conditioner made by Seachem. It is one of the most widely used conditioners in freshwater and saltwater aquariums. Unlike basic dechlorinators that only handle chlorine, Prime also tackles chloramine and can temporarily bind ammonia, nitrite, and nitrate — which makes it useful for water changes and emergency situations.

What Prime does

• Chlorine and chloramine — Tap water contains chlorine or chloramine to kill bacteria. Both are toxic to fish. Prime neutralises them so tap water is safe to add.
• Ammonia and nitrite — Prime can temporarily bind these into a non-toxic form for up to 24–48 hours. It does not remove them; it detoxifies them so fish are not harmed while you fix the cause (e.g. incomplete cycle, ammonia spike).
• Nitrate — In high doses, Prime can also bind nitrate. For routine use, the main benefit is chlorine/chloramine removal.

How to use Prime

For water changes: Dose the new water before or as you add it. The standard dose is 1 cap (5 ml) per 50 litres (about 13 US gallons). Prime is highly concentrated — a little goes a long way. Always follow the label; overdosing is generally safe but can temporarily affect oxygen levels in rare cases.

For ammonia or nitrite emergencies: You can dose up to 5× the normal amount to detoxify a spike. This buys time for water changes and fixing the underlying problem. Prime is not a substitute for water changes or a cycled filter — it is a temporary bridge.

Prime vs other conditioners

Basic conditioners (e.g. API Tap Water Conditioner, Tetra AquaSafe) remove chlorine and chloramine. Prime does that plus ammonia/nitrite binding, so it is often chosen for cycling tanks, emergency spikes, or keepers who want one product for everything. It is more concentrated than many alternatives, so the bottle lasts longer per litre treated.

What Prime does not do

Prime does not remove ammonia, nitrite, or nitrate from the water — it binds them temporarily. Your nitrogen cycle and water changes still do the real work. It also does not replace the need to cycle a new tank or fix overfeeding and overstocking. Use it as a tool, not a crutch.

Quick takeaways

• Prime neutralises chlorine and chloramine for safe tap water.
• It can temporarily detoxify ammonia and nitrite (24–48 hours) in emergencies.
• Dose new water at 1 cap per 50 L; up to 5× for ammonia/nitrite spikes.
• It does not replace cycling or water changes — it buys time.