Seachem Prime – Concentrated Water Conditioner & Ammonia Detoxifier

The one bottle every aquarium needs.

Tap water carries chlorine and chloramine, and every water change or cycling tank risks an ammonia or nitrite spike that can wipe out your fish.

Seachem Prime is the flagship, ultra-concentrated conditioner for fresh and salt water. It removes chlorine and chloramine and detoxifies ammonia, nitrite, and nitrate — converting ammonia into a safe form the biofilter can still use. It's non-acidic (won't touch pH), won't overactivate skimmers, and one 100 mL bottle treats 1,000 US gallons.

Seachem Laboratories has been a chemistry-driven company since 1979, developing its water treatments in-house in Madison, Georgia. Prime reflects that approach: a highly concentrated, filter-safe conditioner engineered so a few milliliters do the work of far larger doses of ordinary dechlorinators.

1. Dose 5 mL (1 capful) per 200 L (50 US gallons) of new water.
2. Add to new water before a change, or to the tank based on total volume.
3. Double-dose safely for high chloramine; up to 5x to detoxify nitrite in an emergency.

Make tap water safe, every time. Add to cart.

Why Seachem Prime

• Complete protection in one bottle: removes chlorine and chloramine while detoxifying ammonia, nitrite, and nitrate — more than a basic dechlorinator does.
• Exceptional concentration: a single 100 mL bottle treats 1,000 US gallons, so a little goes a long way.
• Non-acidic and filter-safe: won't impact pH and detoxifies ammonia into a form the biofilter can still process.
• Works with your system: safe for fresh and salt water and pairs cleanly with the wider Seachem conditioner range.

Best For

Everyday water changes, setting up and cycling new tanks, and emergency ammonia or nitrite spikes in both freshwater and marine aquariums.

What It Does

Removes chlorine and chloramine; detoxifies ammonia, nitrite, and nitrate; detoxifies heavy metals in tap water; supports the natural slime coat. Non-acidic — will not impact pH. For fresh and salt water.

Directions

Use 1 capful (5 mL) for each 200 L (50 US gallons) of new water. For smaller volumes, each cap thread is approximately 1 mL. May be added to the aquarium directly, but better added to new water first; if dosing the tank directly, base the dose on aquarium volume. A sulfur odor is normal. For exceptionally high chloramine, a double dose may be used safely. To detoxify nitrite in an emergency, up to 5x the normal dose may be used. If temperature is above 30 °C (86 °F) and chlorine/ammonia are low, use a half dose.

Available Sizes

50 mL, 100 mL, 250 mL, 500 mL, 1 L, 2 L, 4 L

FAQ

How much Prime do I use per gallon?
Use 5 mL (1 capful) for every 50 US gallons (200 L) of new water. Each cap thread is roughly 1 mL for smaller volumes.

How is Prime different from Safe or AmGuard?
Prime is the all-in-one liquid conditioner for routine use — dechlorination plus ammonia, nitrite, and nitrate detoxification. Safe is the dry concentrate form, while AmGuard is a more targeted ammonia detoxifier for acute spikes.

Can I use Prime in both freshwater and marine tanks?
Yes. Prime is safe for fresh and salt water, and it won't overactivate protein skimmers.