CALCULATOR
CO₂ & Fertiliser Calculator
The pH/KH relationship gives you the CO₂ concentration already in the water. From there the bubble rate and the dosing schedule follow.
Inputs
Current CO₂ (ppm)
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updates as you type
Bubble rate (bubbles/s)
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Fertiliser dose (mL/week)
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Water change (%)
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Algae risk
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The pH/KH/CO₂ relationship assumes nothing else is buffering the water. It is a good guide in a tank with stable KH and a poor one in a tank where aqua soil has driven KH to zero.
CO₂ above 30 ppm is harmful to fish and shrimp. Above 40 ppm it is lethal. The calculator caps its advice at 30 ppm and warns past that.
A 1.0 pH drop from degassed water is the practical confirmation that you have reached roughly 30 ppm, and it is easier to verify than any calculation.
Note. This calculator is a simplified model built on conventional ranges. It is not a measurement of your tank, and no outcome for any plant or animal is guaranteed. Confirm every figure with a test kit before acting on it.