Dechlorinator dosing calculator
Chloramine needs several times the dechlorinator that free chlorine does, because the product has to break the bond as well as neutralise the chlorine.
ppm
mL per 100 L for 1 ppm
%
Dechlorinator to add
3.75mL
- Roughly this many drops
- 75
- Dose before the safety margin
- 3.00
- Dose per litre
- 0.0625 mL/L
- Effective chlorine load
- 1.00 ppm
- Ammonia released from chloramine Breaking chloramine frees ammonia, which the biofilter then has to process.
- 0.0000
- If dosing the whole tank instead
- 18.8
Show the working
- Water being added = 60
- Chlorine in the tap water = 1
- Disinfectant = 1
- Product dose rate = 5
- Safety margin = 25
- Effective chlorine load = 1 * 1 = 1
- Dose before the safety margin = 60 / 100 * 5 * 1 = 3
- Dechlorinator to add = 3 * (1 + 25/100) = 3.75
- Roughly this many drops = 3.75 * 20 = 75
- Dose per litre = 60 > 0 ? 3.75 / 60 : 0 = 0.0625
- Ammonia released from chloramine = 1 > 1 ? 1 * 0.26 * 60 / 1000 : 0 = 0
- If dosing the whole tank instead = 3.75 * 5 = 18.75
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- dose = volume x product rate x chlorine concentration, with a multiplier for chloramine
Overdosing most dechlorinators is harmless within reason; underdosing is not. The safety margin is cheap insurance.
If your supply uses chloramine, use a product that also binds the ammonia released.