Fishless cycling is the modern standard. No animal ammonia poisoning, faster, more predictable. The biofilter colonizes against pure ammonia, then fish go in safely on day 14-21.
Pure ammonia source. Dr. Tim's Ammonium Chloride is the cleanest. Avoid household ammonia (often has surfactants).
Bottled bacteria starter. Dr. Tim's One and Only or Fritz Turbo Start 700. Drops cycle time from 4-6 weeks to 2-3 weeks.
Test kits. Liquid ammonia + nitrite + nitrate. API Master Freshwater or Salifert.
Day 1. Fill tank, dechlorinate. Dose ammonia to 2 ppm. Dose 2x recommended bottled bacteria (split between tank and filter). Heater to 78F. Filter running.
Day 2-7. Test ammonia + nitrite daily. When ammonia drops to 1 ppm, dose back up to 2 ppm. Nitrite will spike (this is normal).
Day 7-14. Ammonia processing accelerates. Nitrite stays high. Continue dosing ammonia to 2 ppm whenever it drops below 1 ppm.
Day 14-21. Ammonia + nitrite both processing within 24 hours of dosing. Nitrate climbing. Test for the 'cycle complete' check: dose to 2 ppm at noon, both ammonia + nitrite at 0 ppm by next noon.
Cycle complete = ammonia + nitrite both 0 within 24h of 2 ppm dose. Do a 50% water change to drop accumulated nitrate. Add fish slowly - 1-3 small fish first, wait 2 weeks, then add more.
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Browse cycling supplies →Yes, with seeded media. A handful of established gravel, a sponge filter from a running tank, or live rock from a cured reef tank populates the bacteria immediately. Cycle can finish in 5-7 days with strong seeding.
Optional but recommended. Dr. Tim's One and Only or Fritz Turbo Start 700 cuts cycle time roughly in half. Without it, you're waiting for nitrifying bacteria to colonize from spore + air.
Nitrite-consuming bacteria (Nitrobacter / Nitrospira) colonize after ammonia-consuming bacteria. The nitrite spike + slow processing is normal between days 7-14. If stuck past day 21, redose bottled bacteria and check pH (should be 6.5-7.5).
Recommendations on this page cross-checked against the following authoritative references and our internal vendor + breeder database.