How to use the Salifert alkalinity test kit
- Place a 4ml water sample in the test vial using the syringe provided.
- Add 4 drops of the indicator solution
- Carefully add, a drop at a time, the reagent. Gently swirl the vial after each addition.
- Continue adding drops until the colour changes from blue/green to orange/red/pink.
- The amount of reagent added can be read from the syringe.
Interpreting the results
The alkalinity level is read off the chart provided and gives an equivalent figure in terms of dKH. This is a measure of carbonate harness, also referred to alkalinity.
dKH can be converted into mg/litre of calcium carbonate, or meq/litre using the following conversion factors.
1 dKH = 17.9 mg/litre (or ppm) calcium carbonate (CaCO3)
1 dKH = 0.357 meg/litre
Recommendations
- Always check the alkalinity of your water source when assessing it’s suitability for aquaponics. This applies to any fish or plant keeping scenario.
- Record both pH and alkalinity levels regularly as they are strongly linked and have a tendency to decline over time.
- A recommended optimum level in an aquaponic system would be in the range 50 – 150 mg/l CaCO3
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