Aquarium pH/GH/KH Adjustment Calculator – Online Dosing Tool

GH (General Hardness) measures dissolved calcium (Ca²⁺) and magnesium (Mg²⁺) ions — essential for fish osmoregulation, shrimp molting, and plant growth. KH (Carbonate Hardness / Alkalinity) measures bicarbonate (HCO₃⁻) and carbonate (CO₃²⁻) ions — it stabilizes pH by buffering against acid swings. Think of GH as "mineral content" and KH as "pH stability buffer."

This usually means your KH is too low (below 3 °dKH). Without sufficient carbonate buffer, natural acids from fish waste, decaying organics, and CO₂ will rapidly lower pH. First raise KH to at least 4–6 °dKH using baking soda or an alkaline buffer, then adjust pH. Also check for old substrate that may be leaching acids.

These calculations are based on manufacturer guidelines and stoichiometric chemistry — they provide a reliable starting point. However, actual results vary due to substrate buffering, dissolved organics, CO₂ levels, and existing water chemistry. Always dose conservatively first (use 70–80% of calculated dose), wait 2 hours, re-test, then fine-tune.

Yes! Plain sodium bicarbonate (baking soda) is one of the safest and most cost-effective KH boosters. Ensure it's pure baking soda without additives (no anti-caking agents, perfumes, or cleaning additives). Food-grade is acceptable. About 3 grams per 100 Liters raises KH by ~1 °dKH. For planted tanks, consider potassium bicarbonate instead to avoid sodium buildup.

It depends on your livestock: Neocaridina shrimp thrive at 6–10 °dGH; Caridina shrimp prefer 3–6 °dGH; most community tropical fish do well at 5–12 °dGH; African cichlids need 10–18 °dGH; Discus prefer soft water at 2–5 °dGH. Planted tanks generally target 4–8 °dGH to ensure sufficient calcium and magnesium for plant uptake.

Unlike raising GH, lowering GH chemically is difficult. The most reliable methods are: (1) Dilute with RO (reverse osmosis) or distilled water — mix to achieve your target. (2) Use a water softener pillow or ion-exchange resin. (3) Add peat moss or Indian almond leaves (minor effect). Our calculator will recommend RO dilution ratios if your target GH is below current levels.

KH acts as a pH buffer — it resists pH changes. Water with KH of 8+ °dKH has a large "buffer capacity" that neutralizes added acids or bases before pH shifts. This is why African cichlid tanks (high KH) are so pH-stable, while soft-water Amazon biotopes (low KH) experience rapid pH swings. Our calculator includes a KH correction factor to adjust doses accordingly.

Yes, but it's specialized. Seachem Equilibrium raises GH using a balanced calcium-magnesium-potassium blend optimized for planted aquariums. It adds K⁺ (potassium) which benefits plants, and uses gluconate-bound minerals for better plant absorption. For fish-only tanks, a simpler CaCl₂ + MgSO₄ DIY mix works equally well at lower cost. Equilibrium dose: ~16g per 80L raises GH by ~3 °dGH.