9.1
Score
Seachem
Seachem Prime Water Conditioner 500ml
★★★★★598 reviews
The best all-in-one water conditioner that detoxifies chlorine, chloramine, and ammonia.
$18.49
Independently tested · Why trust us?
Pros & Cons
✓ What We Love
- Highly concentrated — 500ml treats 5,000 gallons
- Works on both freshwater and saltwater tanks
- Detoxifies ammonia and nitrite in emergencies
- Eliminates chlorine and chloramine from tap water
- Trusted by professional aquarists worldwide
✗ Things to Consider
- Strong sulfur smell when undiluted
- Easy to overdose if not using the measuring cap accurately
- Not a permanent ammonia solution — address root cause
Who Should Buy This?
- ✓All fish keepers doing water changes
- ✓Emergency ammonia spike management
- ✓New tank setups requiring dechlorinated water
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Full Specifications
| Volume | 500ml |
| Treats | Up to 5,000 gallons (at standard dose) |
| Removes | Chlorine, Chloramine, Ammonia, Nitrite, Nitrate |
| Suitable For | Freshwater and Saltwater |
| Dose | 1 capful (5ml) per 200L |
Frequently Asked Questions
Use 1 capful (5ml) for every 200 litres (50 gallons) of new water added. In ammonia emergencies, you can safely dose up to 5x the normal amount.
The sulphur-like odour comes from the active reducing agents that neutralise chlorine and chloramine. It is completely safe and dissipates quickly once diluted in the tank.
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Reviewed by Marcus Chen
Last updated: 2026-03-01 · How we test
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