Coralog's default target ranges (mixed reef)
The "drift" column is how far outside the range still counts as drifting before the app calls it an alert. You can override every range in the app.
| Parameter | Target | Drift band |
|---|---|---|
| Alkalinity | 8.0 – 9.5 dKH | ±0.5 |
| Calcium | 400 – 450 ppm | ±25 |
| Magnesium | 1300 – 1400 ppm | ±50 |
| Nitrate | 2 – 10 ppm | ±5 |
| Phosphate | 0.02 – 0.10 ppm | ±0.05 |
| Salinity | 34 – 35 ppt | ±0.5 |
| Temperature | 76 – 80 °F | ±1.5 |
| pH | 7.9 – 8.4 | ±0.2 |
How the dose is calculated
Every additive label states a reference: some millilitres raise a parameter by some amount in some volume. The needed change scales linearly with your tank volume, so ml = delta × gallons × refMl ÷ (refDelta × refGallons). Litres are converted to US gallons at 3.785 L per gallon. The prefilled reference numbers are neutral placeholders; replace them with your product's label.
Use net water volume, not the tank's nominal size. Rock and sand displace a lot; a "75 gallon" system often holds 55 to 65 gallons of water.
Sources
DosingMath.doseML, the default label references, the target ranges, and the drift bands were copied from Coralog's source on September 17, 2026.
Questions
How do I calculate how much alkalinity to dose?
Take the dosing line on your additive's label, for example 1 ml raises 0.1 dKH in 10 gallons. Dose = (target − current) × your gallons × label ml ÷ (label dKH × label gallons). For a 75 gallon tank going from 7.6 to 8.5 dKH with that label, the dose is 67.5 ml, which the calculator rounds to 68.
What are good reef tank parameters?
Coralog's defaults for a mixed reef are alkalinity 8.0 to 9.5 dKH, calcium 400 to 450 ppm, magnesium 1300 to 1400 ppm, nitrate 2 to 10 ppm, phosphate 0.02 to 0.10 ppm, salinity 34 to 35 ppt, temperature 76 to 80°F, and pH 7.9 to 8.4. Stability matters more than any single number.
How fast can I raise alkalinity?
A widely used rule of thumb is no more than about 1 dKH per day. Larger corrections should be spread over several days with a retest in between. Calcium and magnesium tolerate bigger steps but the same patience applies.
Why does the calculator only raise a parameter?
Additives raise. To bring a value down you dose less or do a water change, which this tool doesn't model. Coralog's dosing calculator has the same guard.
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