Is your ammonia toxic? How big a water change? Exact conditioner & salt dose. Instant. Shows the math. No sign-up.
The same ammonia test reading is harmless at low pH and lethal at high pH. This works out the toxic part (un-ionized NH₃) from your pH and temperature.
Dilution to a target level. Enter your current reading (ammonia, nitrite or nitrate) and the level you want to reach.
Dose for your actual water volume. Pick your product or enter its label rate.
Freshwater salt treatment dose for your volume. Pick a strength.
Toxic ammonia is the un-ionized fraction. We use the standard Emerson (1975) relation: pKa = 0.09018 + 2729.92 / T(K), fraction = 1 / (1 + 10^(pKa − pH)), then NH₃ = total ammonia × fraction. Freshwater, salinity ≈ 0. Every step is shown above so you can check it.
A water change dilutes by the fraction of water you swap: new level = current × (1 − fraction). To reach a target, fraction = 1 − (target ÷ current). If that is above ~50%, we split it into several safer changes.
Conditioner and salt are simple proportions of your actual water volume — which is why entering the real volume (not the tank's rated size) matters.