Hardness conversions
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| Unit | Value | Typical use |
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Hoe de berekening werkt
1 dGH = 17.86 ppm CaCO₃ = 0.357 meq/L. Same conversion applies to dKH (carbonate hardness) because both are reported as calcium-carbonate equivalent. ppm and mg/L are interchangeable for dilute aquarium water.
Temperature: °C = (°F − 32) × 5/9. Most freshwater tropicals sit at 24–27 °C (75–80 °F). Discus prefer 28–30 °C; goldfish 18–22 °C. Always match new water to existing tank temperature within 1 °C to avoid stressing fish.