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Dechlorinator Dosage Calculator
How much water conditioner for your water change? Pick your product and get the exact mL — especially handy for small tanks where a capful is way too much.
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Calculate conditioner dose
Label doses used by this calculator
- Seachem Prime — 1 capful (5 mL) per 50 US gallons of new water (0.1 mL/gal, about 2 drops per gallon). Detoxifies chlorine, chloramine, ammonia, nitrite and nitrate. Emergency nitrite detox: up to 5× normal dose.
- Tetra AquaSafe Plus — 1 teaspoon (5 mL) per 10 gallons. Neutralizes chlorine/chloramine and adds protective colloids.
- API Tap Water Conditioner — 1 mL per 20 gallons to remove chlorine and detoxify heavy metals. It is very concentrated — a little goes a long way. Chloramine dosing is higher; follow your bottle.
Dosing tips
- Dose the new water, not the tank — unless you add conditioner straight into the aquarium before refilling, in which case dose for the full tank volume.
- Small tanks need a syringe, not a capful. A 5-gallon water change needs just 0.5 mL of Prime — use a 1 mL syringe for accuracy.
- Add conditioner to the new water before it touches the tank, and match the temperature.
- Prime's sulfur smell is normal. A slight overdose of most conditioners is harmless, but gross overdosing can deplete oxygen — measure, don't pour.
Frequently asked questions
How much Prime per gallon?
0.1 mL per gallon (1 capful / 5 mL per 50 gallons) — about 2 drops per gallon.
How much AquaSafe for a 10-gallon water change?
1 teaspoon (5 mL) treats 10 gallons.
Can I overdose water conditioner?
Slight overdoses are harmless, but large overdoses of some conditioners can bind oxygen. Measure with a syringe for small volumes.
Do I treat the whole tank or just new water?
Just the new water — unless you dose directly into the tank before refilling, then dose for total tank volume.
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