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GH & KH Hardness Ratio Calculator for Shrimp Tanks

Aquarium Water Chemistry aquarium calculator GH KH
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Water Hardness Input
dGH
Typical: 4–8 dGH for shrimp
dKH
Typical: 0–6 dKH for shrimp
Quick Presets:
Neo Ideal Caridina Ideal Sulawesi RO Water
GH : KH Ratio
2.00 : 1
Ideal for Neocaridina
GH = 6.0 dGH | KH = 3.0 dKH
KH≫GH Sulawesi Neocaridina High Ratio KH→0
Neocaridina
Cherry, Blue Dream
GH: 6–8 dGH
KH: 3–6 dKH
Ratio: 1.2:1 – 3:1
Enter values
Caridina
Crystal, Bee, Taiwan
GH: 4–6 dGH
KH: 0–2 dKH
Ratio: 2:1 – ∞ (KH→0)
Enter values
Sulawesi
Cardinal, Harlequin
GH: 6–8 dGH
KH: 4–6 dKH
Ratio: 1:1 – 1.5:1
Enter values
Amano
Caridina multidentata
GH: 6–8 dGH
KH: 3–5 dKH
Ratio: 1.5:1 – 2.5:1
Enter values
Recommendation

Your GH:KH ratio of 2.00:1 falls within the ideal range for Neocaridina shrimp. Both GH and KH are at good levels. This water is well-suited for Cherry, Blue Dream, and other Neocaridina varieties. For Caridina species, consider lowering KH closer to 0–2 dKH.

Frequently Asked Questions
GH (General Hardness) measures the concentration of calcium (Ca²⁺) and magnesium (Mg²⁺) ions in your aquarium water. These minerals are essential for shrimp to build and maintain their exoskeletons. KH (Carbonate Hardness) measures carbonate (CO₃²⁻) and bicarbonate (HCO₃⁻) ions, which act as a pH buffer. KH prevents sudden pH swings that can stress or kill shrimp. Together, the GH:KH ratio determines whether your water is suitable for specific shrimp species.
Neocaridina shrimp (Cherry, Blue Dream, Yellow, etc.) thrive with a GH of 6–8 dGH and KH of 3–6 dKH, giving an ideal GH:KH ratio of approximately 1.2:1 to 3:1. The sweet spot is around 1.5:1 to 2:1 (e.g., GH 6, KH 3). They need sufficient KH to ensure stable pH and proper molting. If KH drops too low (< 2 dKH), pH can swing dangerously. If GH is too high (> 10), it can cause molting problems.
Caridina shrimp (Crystal Red, Crystal Black, Bee, Taiwan Bee) prefer GH of 4–6 dGH and KH as low as 0–2 dKH. The GH:KH ratio is typically 2:1 or higher, and when KH = 0, the ratio is effectively infinite—which is perfectly acceptable for these sensitive shrimp. Many experienced Caridina keepers use active buffering substrates (like ADA Amazonia) to drive KH to near zero while maintaining a stable low pH around 5.5–6.5. Low KH means less buffering capacity, so consistent maintenance is critical.
When KH drops below 2 dKH, the water loses its buffering capacity, making pH vulnerable to sudden drops (often called a "pH crash"). This is especially dangerous for Neocaridina shrimp, which prefer stable pH around 6.8–7.5. A pH crash can cause osmotic shock, failed molts, and death. However, Caridina shrimp are adapted to low-KH environments and actually thrive with KH near 0 when paired with acidic buffering substrates. Always know which species you're keeping before adjusting KH.
To increase GH: Use commercial remineralizers like Salty Shrimp GH+ (for Caridina) or Salty Shrimp GH/KH+ (for Neocaridina). You can also use crushed coral or aragonite in the filter, but these also raise KH. To increase KH: Add crushed coral, aragonite, or baking soda (sodium bicarbonate) in very small, measured amounts—1/8 tsp per 10 gallons raises KH by ~1 dKH. To lower GH/KH: Dilute with RO (reverse osmosis) or distilled water. Mix RO water with tap water to achieve target parameters. Always make changes gradually over several days to avoid shocking your shrimp.
The conversion factor is: 1 dGH = 17.86 ppm (as CaCO₃ equivalent) and 1 dKH = 17.86 ppm (as CaCO₃ equivalent). For quick mental math, multiply dGH/dKH by ~18 to get ppm, or divide ppm by ~18 to get degrees. For example: 6 dGH ≈ 107 ppm, and 3 dKH ≈ 54 ppm. Most aquarium test kits (like API) display results in both units. Use our calculator above to instantly see both values.
Yes, but only certain species. Caridina shrimp (Crystal Red, Bee, Taiwan Bee) can thrive with KH = 0 when kept with active buffering substrate that maintains a stable acidic pH. However, Neocaridina and Sulawesi shrimp need at least 2–3 dKH for pH stability and proper molting. A KH of 0 with no active substrate is risky for any shrimp because pH can swing wildly. If you intentionally maintain KH = 0 for Caridina, you must use RO water remineralized with GH+ only and an appropriate buffering substrate.
Test GH and KH at least once per week in established shrimp tanks. Test more frequently (every 2–3 days) in newly set up tanks, after water changes, or when you're adjusting parameters. Shrimp are sensitive to gradual mineral depletion—as plants and shrimp consume calcium and carbonates, GH and KH can slowly drop over time. Regular testing helps you catch trends before they become problems. Always test your source water (tap or RO) before mixing to know your baseline.
For Neocaridina: Use a GH/KH+ remineralizer (like Salty Shrimp GH/KH+) which raises both GH and KH in a balanced ratio of approximately 1:0.5 (GH:KH). This matches Neocaridina requirements perfectly. For Caridina: Use a GH+ only remineralizer (like Salty Shrimp GH+) which raises GH without adding KH. This allows you to maintain the low-KH environment Caridina prefer. For Sulawesi: Use specialized Sulawesi mineral mixes that replicate their unique lake water parameters with higher KH and specific trace elements. Always mix remineralizer into RO water—never add directly to the tank.
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