Net water, not tank rating. Use the Tank Volume calculator if you have not measured it.
Ammonia dose to start a cycle, plus the nitrate and alkalinity that show up when it finishes.
Doses 284 L to 2.0 ppm ammonia nitrogen using Dr Tim's Ammonium Chloride. Hold temperature near 27 °C, keep the lights off, and skip the water changes until it finishes.
mL = 2.00 ppm N × 283.9 L ÷ 40 mg N per mL = 14.2 mL
Ammonium chloride NH₄Cl has a molar mass of 53.489 g/mol carrying 14.007 of nitrogen, a mass fraction of 0.2619. One gram in one litre gives 261.9 ppm ammonia nitrogen.
Test kits report total ammonia, which is NH₃ plus NH₄⁺, almost always expressed as nitrogen. This calculator works in the same unit, so what you dose is what the kit should read.
Nitrification runs in two steps. Ammonia oxidisers turn NH₄⁺ into nitrite, then nitrite oxidisers turn nitrite into nitrate. The second group grows more slowly, which is why nitrite lingers after ammonia has gone.
The stoichiometry is NH₄⁺ + 2 O₂ → NO₃⁻ + 2 H⁺ + H₂O. Two moles of acid per mole of nitrogen means every ppm of ammonia nitrogen destroys about 0.4 dKH of alkalinity. A cycle that stalls halfway is often a cycle that ran out of buffer.
It also means every ppm of ammonia nitrogen you dose comes back as 4.43 ppm of nitrate, so a tank cycled at 2 ppm three times over finishes near 27 ppm nitrate. A large water change before adding livestock is part of the process, not a sign something went wrong.
Household ammonia works only if it is clear, unscented, and free of surfactants. Shake the bottle. If it foams, do not use it. Strength varies between brands, so treat the figures here as approximate and confirm with a test kit after the first dose.
The tank is cycled when a full dose of ammonia goes to zero ammonia and zero nitrite within 24 hours. Anything short of that is a tank that will crash when you add fish.
Sources: Dr Tim's Ammonium Chloride · Dr Tim's fishless cycling guide