Calculate how much GH booster and baking soda to add to RO/DI water to reach your target GH and KH for planted tanks and shrimp.
Reverse-osmosis (RO) and RO/DI water is effectively pure H2O with near-zero general hardness (GH) and carbonate hardness (KH). Pouring it straight into a tank crashes pH, starves osmoregulating fish and shrimp, and provides no buffer against acidification. This calculator turns your desired GH and KH in dGH/dKH and your container's water volume into precise gram amounts of GH-boosting equilibrium salts and baking soda for KH, the cheapest reliable remineralization route for shrimp and planted tanks.
1 dGH equals 17.86 ppm CaCO3 equivalent, and equilibrium salts (calcium sulfate, magnesium sulfate, potassium sulfate blend) raise GH at roughly 0.5 g per 10 L per dGH depending on the brand. KH is raised separately with sodium bicarbonate at roughly 0.067 g per 10 L per dKH. The calculator multiplies your target dGH and dKH by these coefficients and returns total grams for the container you are mixing. Always pre-mix in a clean storage barrel, never directly in the tank.
Enter your target GH (general hardness in °dGH) and target KH (carbonate hardness in °dKH), and the volume of RO/DI water you are mineralizing. The calculator outputs grams of GH booster (for GH) and baking soda NaHCO3 (for KH).
The GH booster raises GH by adding calcium, magnesium, and potassium. Baking soda raises KH (carbonate alkalinity) with minimal effect on GH. Dissolve each product in a small amount of RO water before adding to the bucket.
For caridina shrimp tanks, substitute potassium bicarbonate (KHCO3) for baking soda at the same dose — it avoids adding sodium. For GH-only adjustments (when KH is already correct), use the GH booster alone.
RO (reverse osmosis) and DI water has near-zero minerals, which is too soft for most fish and plants. Fish need minerals (Ca, Mg, K) for proper osmoregulation, and plants need them for metabolic functions. Remineralizing lets you dial in exact GH and KH.
For most planted tanks: GH 4–8 °dGH, KH 3–5 °dKH. For soft-water fish (discus, cardinal tetra): GH 1–4, KH 1–3. For shrimp (neocaridina): GH 6–8, KH 2–4. For shrimp (caridina): GH 4–6, KH 0–2 (use different mineralizer).
The GH booster (calcium/magnesium/potassium supplement) raises GH (general hardness) by adding calcium, magnesium, and potassium — the minerals fish and plants need. It does not raise KH (carbonate hardness). Use it to target GH independently of KH.
Yes. Baking soda (sodium bicarbonate, NaHCO3) effectively raises KH. It adds a small amount of GH as a side effect. For shrimp tanks where sodium is a concern, use potassium bicarbonate (KHCO3) instead — the dose is similar.
Always pre-mix in a bucket of RO water first. Add the GH booster and baking soda to the bucket, stir until dissolved, then add to the tank. Adding powder directly to a tank with fish can cause localized parameter spikes and stress fish.