Seachem AmGuard – Emergency Ammonia Detoxifier (500 mL)

Your emergency answer to a dangerous ammonia spike.

An ammonia spike is a silent killer — and when levels climb fast, you need something that acts within minutes and keeps working.

Seachem AmGuard is the strongest liquid ammonia binder on the market. It detoxifies toxic free ammonia within minutes and doesn't degrade for nearly 72 hours — at least twice as long as competitors — converting it to a safe form the biofilter can still use. It's safe during cycling, works in fresh or salt water, and won't alter pH, KH, or GH. It also removes chlorine and chloramine.

Seachem Laboratories has been a chemistry-driven company since 1979, developing its water treatments in-house in Madison, Georgia. AmGuard reflects that lab-led approach: a highly concentrated binder engineered to lock up free ammonia faster and hold it longer than ordinary detoxifiers, without disturbing the water chemistry around it.

1. Dose 5 mL (1 capful) per 200 L (50 US gallons) daily, or as needed.
2. Increase the dose to match a measured ammonia level in emergencies.
3. For long-term control, pair with Stability and Matrix.

Keep it on hand before the spike hits. Add to cart.

Why Seachem AmGuard

• Longest-lasting protection: detoxifies free ammonia within minutes and keeps working for up to 72 hours — at least twice as long as competing binders.
• Highly concentrated: a single 5 mL capful treats 200 L (50 US gallons), and dosing scales precisely to a measured ammonia level.
• Chemistry-neutral and cycling-safe: won't alter pH, KH, or GH, and converts ammonia into a form the biofilter can still use, so it's safe during cycling.
• Works with your system: also removes chlorine and chloramine, suits fresh and salt water, and pairs with Stability and Matrix for long-term ammonia control.

Best For

Acute ammonia emergencies, new or cycling tanks, and any situation where free ammonia climbs fast and needs to be locked down for days — in both freshwater and marine aquariums.

What It Does

Rapidly detoxifies toxic free ammonia for up to 72 hours; ideal for emergencies and safe during cycling. Also removes chlorine and chloramine. Does not alter pH, KH, or GH. For fresh and salt water.

Directions

Use 1 capful (5 mL) for every 200 L (50 US gallons) daily or as needed to reduce ammonia. With a MultiTest Free & Total Ammonia kit, use 1 capful per 40 L (10 US gallons) to remove 1 mg/L of free ammonia. Do not use if water temperature is above 30 °C (86 °F). Note: standard ammonia test kits can give a false positive reading while AmGuard is in use.

Size

500 mL

FAQ

How long does AmGuard keep ammonia detoxified?
It detoxifies free ammonia within minutes and holds it in a safe form for up to 72 hours — at least twice as long as many competing binders.

Is AmGuard safe to use while my tank is cycling?
Yes. It converts free ammonia into a form the biofilter can still use, so beneficial bacteria continue to establish while your fish are protected.

Why is my ammonia test still reading high after dosing?
Standard ammonia test kits can show a false positive while AmGuard is in use. A Seachem MultiTest Free & Total Ammonia kit distinguishes the toxic free ammonia from the detoxified form.