Water Parameter Converter
Convert between dKH/ppm, dGH/ppm, temperature and salinity units.
How it works
Hardness: 1 dKH = 17.86 ppm CaCO3; 1 dGH = 17.86 ppm. Temperature: C = (F − 32) × 5/9. Salinity: 1.025 specific gravity ≈ 35 ppt ≈ 53 mS/cm.
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Formula & Method
Hardness: 1 dKH = 17.86 ppm CaCO3; 1 dGH = 17.86 ppm. Temperature: C = (F − 32) × 5/9. Salinity: 1.025 specific gravity ≈ 35 ppt ≈ 53 mS/cm.
Example Calculation
A KH test reading of 4 dKH = 4 × 17.86 = 71.4 ppm. 25C = (25 × 9/5) + 32 = 77F.
Frequently Asked Questions
How do I convert dGH to ppm?
Multiply dGH by 17.9. So 8 dGH is about 143 ppm. The same factor converts dKH to ppm as CaCO3.
What is the difference between GH and KH?
GH measures calcium and magnesium, which matter for shrimp moulting, livebearer health and plant nutrition. KH measures carbonate buffering, which stabilises pH. They are independent - water can be high in one and low in the other.
What KH do I need for stable pH?
At least 3-4 dKH for reliable stability. Below that, pH can swing sharply with CO2 injection or organic acid build-up, which is harder on fish than a steady pH at the wrong value.
Is Melbourne tap water hard or soft?
Melbourne's supply is relatively soft compared with most Australian capitals, though it varies by supply zone and suburb. Test your own tap water rather than relying on a citywide figure - it is the most useful single test before choosing species.