Care Guides
How Much Aquarium Salt Should I Add?
How much aquarium salt to add per litre for tonic and treatment doses, which fish tolerate salt, and how to remove it safely, with a free salt calculator.
Read more →Aquarium Salt Calculator
Salt to add
79 g
In tablespoons
5.3
approx. (15 g each)
Dissolve salt in tank water before adding. Salt only leaves through water changes. Check your fish and plants tolerate salt first.
Work out how much aquarium salt to add to your tank. Enter your water volume and choose a dose level to get the amount in grams and tablespoons for tonic or treatment use.
How to dose aquarium salt
Aquarium or tonic salt is dosed by water volume. A common mild tonic dose is one tablespoon, about 15 grams, per 19 litres or 5 US gallons. Stronger treatment doses use one tablespoon per 11 litres or per 8 litres. Always dissolve the salt in a cup of tank water before adding it, dose to the real water volume, and remember that salt only leaves through water changes, not evaporation. Check that your fish and plants tolerate salt before treating.
Aquarium salt dose by tank volume
| Litres | Mild tonic (g) | Medium dose (g) | Strong dose (g) |
|---|---|---|---|
| 20 | 16 | 27 | 38 |
| 40 | 32 | 55 | 75 |
| 60 | 47 | 82 | 113 |
| 100 | 79 | 136 | 188 |
| 150 | 118 | 205 | 281 |
| 200 | 158 | 273 | 375 |
| 300 | 237 | 409 | 563 |
Calculated with the same formula as the calculator above. Values are rounded.
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Frequently asked questions
How much aquarium salt should I add?
A mild tonic dose is about one tablespoon (15 grams) per 19 litres or 5 US gallons. Enter your volume and dose level above for the exact grams and tablespoons.
How much is a tablespoon of aquarium salt?
A level tablespoon of aquarium salt weighs roughly 15 grams, though this varies a little with grain size.
Do all fish tolerate salt?
No. Many scaleless fish, such as some catfish and loaches, and many live plants are sensitive to salt, so check your species before dosing.
Does salt leave the tank on its own?
No. Salt does not evaporate, so it only leaves through water changes. Top-ups for evaporation should be fresh water with no added salt.
Should I dose to tank volume or water volume?
Use the real water volume, after subtracting substrate and decorations, so you do not overdose a tank that holds less water than its rated size.
How do I remove salt from the aquarium?
Do repeated partial water changes with fresh, unsalted water. Each change dilutes the remaining salt until it is back to zero.
Related guides
Learn the core ideas behind fish tank volume before or after using the calculator.
Setup Guides
How to Cycle a Fish Tank (Before You Add Fish)
Cycling a new aquarium builds the bacteria that keep fish safe. The nitrogen cycle explained simply, plus a step-by-step fishless cycle.
Read more →Maintenance Guides
How to Clean a Fish Tank Without Killing the Bacteria
A simple aquarium cleaning routine: how much water to change, how to vacuum gravel and clean the glass without harming your filter bacteria or stressing fish.
Read more →