API Ammo Lock

• Acts on contact – the ammonia is locked into a non-toxic form as soon as it disperses, which matters when a filter has crashed at 11pm.
• Handles tap water too – detoxifies chlorine and chloramine, so it does the conditioner's job during an emergency top-up.
• Leaves the nitrogen cycle running – the locked ammonia is still available to the nitrifying bacteria, so the tank continues to cycle rather than stalling.
• 1.5c to 2.6c per litre treated – cost per litre varies by size, and the bigger bottle is not always the cheapest, so it is worth checking the table below rather than assuming.
• Freshwater and saltwater – one bottle for both systems.
• Four sizes – a 30 mL bottle for a quarantine tub or travel kit through to 473 mL for a fishroom.

Both figures are transcribed from the manufacturer's published documents rather than paraphrased. Checked 7 August 2026.

What each bottle covers

These volumes are calculated from API's stated rate of 5 mL per 38 L. API's own 237 mL pack quotes up to 1,779 L, which is the same figure rounded down at the gallon conversion. Cost per litre is worked from current pricing and does not move in a straight line with size – the 118 mL bottle is the most expensive of the four per litre treated, not the smallest 30 mL trial bottle, so check the table before assuming bigger is always cheaper.

Suitable for

• Freshwater and saltwater aquariums showing an ammonia reading above zero
• New tanks part-way through cycling with fish already in them
• Quarantine and hospital tubs with no established filter
• Emergency water changes where the tap supply is chloraminated

Not suitable for

• Replacing a water change. Detoxified ammonia is still in the water; dilution is still the fastest way to reduce it.
• Propping up a permanently overstocked or underfiltered tank. Repeat dosing week after week is treating a symptom.
• Correcting a nitrite or nitrate problem. It acts on ammonia, chlorine and chloramine only.
• Reef tanks where you want certainty about invertebrates. API lists the product for freshwater and saltwater aquariums but publishes no specific coral or invertebrate statement, so on a stocked reef we would do a water change first.

• Keep the cap tight and store below 38 °C. A hot car boot in a Queensland summer is outside that range.
• Shake before use and dose into a high-flow area so it disperses quickly.
• Keep out of reach of children. In Australia, if it is swallowed or splashed in the eyes, call the Poisons Information Centre on 13 11 26 and follow the first aid advice printed on your bottle.

• API Ammonia Test Kit – you cannot dose to "until ammonia is not detected" without testing for it.
• API Freshwater Master Test Kit – covers ammonia, nitrite, nitrate and pH, which is the full picture during a cycle.
• API Quick Start – adds the nitrifying bacteria that do the permanent job Ammo-Lock is buying time for.
• The full API range – conditioners, treatments and test kits built to work together.

Nothing here limits your rights under the Australian Consumer Law. If a bottle arrives damaged, leaking or short-dated, contact us for a replacement.

Freight is standard. All four sizes are under 500 mL and ship as ordinary parcels with no dangerous goods surcharge.

Why does my ammonia test still read high after dosing Ammo-Lock?

Because that is how the product works. API's label states Ammo-Lock does not remove ammonia – it converts it to a non-toxic form, and the water will still test positive until the biological filter processes it out. The reading tells you total ammonia is present, not that your fish are being harmed by it.

Does API Ammo-Lock replace a water change?

No. A water change physically removes ammonia; Ammo-Lock only makes what is there less harmful. The right move during a spike is a water change first, then Ammo-Lock on the remaining volume.

Can I use Ammo-Lock as my everyday water conditioner?

It detoxifies chlorine and chloramine at the same 5 mL per 38 L dose, so it will do the job. Most keepers use it as the emergency bottle and keep a dedicated conditioner with a slime coat additive for routine water changes.

Is it safe in a saltwater tank?

API lists Ammo-Lock for both freshwater and saltwater aquariums. The label makes no specific statement about corals, anemones or other invertebrates, so on a stocked reef treat that as unverified and reduce ammonia by water change instead.

Will it stall my tank's cycle?

No. The locked ammonia remains available to nitrifying bacteria, which is why the water keeps testing positive. The cycle continues while the fish are protected.

Which size should I buy?

A 200 L tank uses about 26 mL per dose. The 118 mL bottle carries roughly four full-tank doses at that volume, the 237 mL about nine, and the 473 mL about eighteen. The 30 mL bottle suits a quarantine tub or a travel kit rather than a display tank. On cost per litre alone the 473 mL and 237 mL work out cheapest; the 118 mL is the one size that does not represent good value per litre, though it may still suit you as a smaller commitment.