Seachem MultiTest Ammonia – Free & Total Ammonia Test Kit

Read True Ammonia Even While Treating Your Tank

Free ammonia is the toxic form that harms fish, yet most test kits can't measure it, and they give false readings when you're dosing an ammonia remover. That leaves you guessing whether your water is actually safe.

MultiTest Ammonia measures total (NH3 and NH4+) and free ammonia (NH3 only) down to less than 0.05 mg/L and is virtually interference free in marine and fresh water. Built on the same gas exchange technology as Seachem's Ammonia Alert, it is the only kit on the market that can read free ammonia even while using removal products like Prime, Safe, and AmGuard, unlike salicylate or Nessler kits that raise the pH to 12 or greater and release ammonia for a false reading.

Like every MultiTest kit, this one comes from Seachem Laboratories, the chemistry-driven company founded in 1979 in Madison, Georgia, USA, where products are developed in-house by its own chemists. That reagent-based engineering is exactly why MultiTest Ammonia is prized for its accuracy and sensitivity: its gas exchange chemistry isolates the truly toxic free ammonia rather than being fooled by ionized ammonia or by ammonia-removal treatments, so the number you read reflects what your fish actually experience.

1. Test your water to measure both total and free ammonia.
2. Focus on the free ammonia result, the toxic form that matters most.
3. Retest with confidence even while dosing ammonia removers.

Know exactly how safe your water really is. Add to cart.

What It Does

This kit measures total (NH3 and NH4+) and free ammonia (NH3 only) down to less than 0.05 mg/L and is virtually interference free in marine and fresh water. Free ammonia is the toxic form of ammonia (vs. ionized ammonia NH4+ which is non-toxic), so it is much more important to keep an eye on the level of free ammonia in your system. It is based on the same gas exchange technology used in the Ammonia Alert and is the only kit on the market that can read levels of free ammonia while using ammonia removal products such as Prime, Safe, AmGuard and similar competing products. Other kits (salicylate or Nessler based) determine total ammonia by raising the pH of the test solution to 12 or greater, at which point all ammonia removal products break down and re-release the ammonia, giving a false ammonia reading.

Why Seachem MultiTest Ammonia

• Reads free ammonia, the toxic form: it measures both total (NH3 and NH4+) and free ammonia (NH3 only) down to less than 0.05 mg/L, so you track the fraction that actually harms fish.
• Works while dosing removers: the only kit that can read free ammonia even while using Prime, Safe, AmGuard, and similar products, so your treatment doesn't skew the result.
• High sensitivity and accuracy: built on the same gas exchange technology as the Ammonia Alert and virtually interference free in both marine and fresh water.
• Avoids false positives: unlike salicylate or Nessler kits that raise pH to 12 or greater and re-release ammonia, its chemistry does not trigger a misleading reading.

Best For

Ideal for cycling new tanks, monitoring quarantine and hospital setups, and confirming water safety whenever you are dosing an ammonia remover. It suits both marine and freshwater aquarists who want a precise, interference-free read on the toxic free ammonia level.

FAQ

Freshwater or saltwater? It works in both marine and fresh water and is virtually interference free in each.

Does it read total or free ammonia? Both. It measures total (NH3 and NH4+) and free ammonia (NH3 only) down to less than 0.05 mg/L, with free ammonia being the toxic form to watch.

Can I test while using an ammonia remover? Yes. It is the only kit that can read free ammonia while using removal products such as Prime, Safe, and AmGuard, where salicylate or Nessler kits would give a false reading.