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Ammonia Calculator

When completing a fishless tank cycle, in the absence of fish waste, it is necessary to dose an ammonia source to feed and promote the colonisation of beneficial bacteria in your biological filter. 


This simple calculator will help guide you to determine the correct dosage of a liquid ammonia source (see notes below).


Please read our article and step by step guide to learn more about fishless tank cycling.

Fishless Tank Cycle

Ammonia Dosage Calculator

Click to Calculate/Update

Press Calculate to see the result!


Source of ammonia*: You should select an ammonia solution free from surfactants or perfumes. Read the label carefully to ensure no additives. If you shake the closed bottle and there is foam, this is a good indicator that surfactants are present. Typically household ammonia solutions with a concentration of 5 to 10% are suitable.  


Aquarium Volume**: You may already know your aquarium volume (capacity), or you can use our simple calculator. However, this will be the volume of the unfurnished aquarium, and it does not take into account the displaced volume due to substrate, décor – rocks, wood etc. Although this will depend on your specific set-up, the furnished aquarium's volume will typically be approximately 85-95% of that value. 

Disclaimer: Information provided for dosing liquid ammonia to your aquarium is a guide for fishless cycling purposes. Ammonia is highly toxic to fish and therefore do not add to aquariums that contain fish. Handle the liquid ammonia appropriately - at high concentrations, it is corrosive and can burn your skin. 

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Items required or that may be useful during a fishless cycle:

Water Parameter Test Kit (essential): ​You will need to test for ammonia, nitrite and nitrate during the cycle. Knowing your aquariums water hardness, both KH and GH, will also help keep your tank cycle on track. The Freshwater Aquarium Test Kit supplied by NT Labs has all the tests you require and represent a good choice for beginners and experienced aquarist alike.​​

Water Conditioner (essential): Tap water will contain either chlorine or chloramine, both toxic to fish and your beneficial bacteria. The use of a water conditioner that neutralises these is therefore essential. A good reliable brand is Tetra AquaSafe.

Liquid Ammonia Source (essential): A liquid ammonia source is the easiest method to initiate and maintain the nitrogen cycle when undertaking a fishless tank cycle. As mentioned in the notes, a liquid household ammonia solution is suitable as long as it is free from additives. One possible choice is Knock Out Household Ammonia, but check the ingredient description before buying as manufacturers sometimes change their formulations.

Measuring Syringe (helpful): When dosing the required ammonia during the fishless cycle, your will need to measure the quantity accurately. Cheap disposable measuring syringes offer a convenient method, especially with the smaller dosages required for smaller aquariums.​​ Several suppliers with different dosing volumes are available via Amazon, by way of an example these dose up to 10ml and would be suitable in most instances. Use the calculator to determine your largest dosage based on 0 starting ammonia and then select a syringe at or slightly greater than this volume.

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