Recipe Calculator

Enter your concentrate strengths (ppm as CaCO₃), base water, and your target profile. The app keeps your latest numbers, works offline, and can sync when you unlock with Face ID/Touch ID.

Inputs

Final volume (L)

Base water TDS (ppm)

GH concentrate strength (ppm as CaCO₃)

KH concentrate strength (ppm as CaCO₃)

Target GH (ppm as CaCO₃) suggested 80

Target KH (ppm as CaCO₃) suggested 40

Base water KH (ppm as CaCO₃) optional — default 25 for Cape Town

If unknown, leave 25. This lets us account for the buffer already in your under-counter water.

Results

GH to add (mL)

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KH to add (mL)

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Top-up water (mL)

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Predicted final GH

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Predicted final KH

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Est. final TDSapprox

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TDS is a conductivity-based proxy and not exactly GH+KH. The estimate shown here is base TDS + target GH + ΔKH.

One-line instructions

Copy

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Concentrate Maker

Mix your own GH/KH concentrates at any strength. Enter desired ppm (as CaCO₃) and the bottle size you want to make. Use Epsom salt (MgSO₄·7H₂O) for GH and Sodium bicarbonate (NaHCO₃) or Potassium bicarbonate (KHCO₃) for KH.

GH concentrate target (ppm) Bottle size (mL)

Epsom salt to add

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Formula: 1 g/L Epsom ≈ 406 ppm as CaCO₃ → grams = target_ppm / 406 × (mL/1000).

KH concentrate target (ppm) Bottle size (mL)

Buffer salt

Bicarb to add

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Conversions: NaHCO₃ → 1 g/L ≈ 595 ppm; KHCO₃ → 1 g/L ≈ 500 ppm (both as CaCO₃).

How to mix

1) Add salts to a clean bottle.
2) Add ~200–300 mL warm RO/distilled, swirl to dissolve.
3) Top up to the exact bottle volume, cap, label, shake.
Labels: “GH conc — XXXX ppm (Epsom)” / “KH conc — XXXX ppm (NaHCO₃ or KHCO₃)”.

★For V60: magnesium-based GH highlights clarity and sweetness. Keep KH modest (≈40 ppm target) for lively—but not sharp—acidity.

Sync & device unlock

Works offline first. When you want the latest values on another device, unlock with Face ID/Touch ID and we’ll sync via Cloudflare KV.

Sync disabled • offline only

Helpful Hints

Base recipe (closest): target ~80 ppm GH and ~40 ppm KH. If your base water already has KH (Cape Town often ~20–30 ppm), the calculator subtracts that automatically (ΔKH).
Small KH bump (+3 ppm) often makes the cup rounder and more forgiving to small grind changes without dulling the top end.
If mid‑palate feels a touch light, prefer a tiny calcium bump over more magnesium: CaCl₂·2H₂O ≈ 680 ppm per g/L → for +5 ppm: 0.00735 g/L (≈ 0.0147 g for 2.0 L).
Avoid stacking big Mg bumps with higher KH — it can sharpen edges and narrow the sweet spot.
TDS is not GH+KH. Use it only as a sanity check; taste and a simple KH/GH drop kit tell the real story.