:INFO Every beginner aquarium guide tells you to "cycle the tank first." Almost none \ give you the numbers. How much ammonia do you add? When do you re-dose? What does the nitrite spike mean, and when does it end? This tutorial answers all of that. The fishless method described here grows the bacterial colony that converts toxic ammonia to harmless nitrate without putting a single fish at risk. It takes 4 to 6 weeks from a cold start, or under a week if you use a bottled bacteria product. Every threshold here comes from Dr. Tim's Aquatics fishless cycling protocol and the consensus ppm targets used across the hobby. :IMAGE :STATS [icon:CLOCK] Total time | 4 to 6 weeks (cold start) or 5 to 7 days (with bottled bacteria) [icon:TARGET] Active effort | About 10 minutes per day to test and re-dose [icon:FIRE] Difficulty | Beginner, no prior experience needed [icon:CHART] Cost of test kit and ammonia | Around $30 to $50 USD :INFO Step 1. Set up the tank and run it for 24 hours first Fill the tank with tap water. Add a dechlorinator (sodium thiosulfate drops, such as Seachem Prime) to neutralise chlorine and chloramines: chlorine kills the bacteria you are trying to grow. Run the filter and heater for a full 24 hours before adding anything else. Heater sizing: use 3 to 5 watts per gallon. A 20-gallon tank needs a 60 to 100W heater. Set the temperature to 80 to 84 F (27 to 29 C): nitrifying bacteria grow fastest in warm water. A tank cycling at 76 F takes noticeably longer than one at 82 F. Filter sizing: aim for 4 to 6 times the tank volume per hour (GPH). A 20-gallon tank needs a filter rated at least 80 to 120 GPH. Buy one rated higher than the minimum: media resistance cuts the real-world flow rate by 30 to 50 percent versus the box rating. :INFO Step 2. Dose ammonia to 2 to 4 ppm You need a pure ammonia source: either Dr. Tim's Ammonium Chloride solution or plain hardware-store ammonia with no surfactants (shake the bottle and check for bubbles: if it foams, it has soap and will kill your bacteria). Using the Dr. Tim's product, 4 drops per gallon raises ammonia by approximately 2 ppm. Dose to 2 to 4 ppm on day one. Confirm the level immediately with a liquid test kit (the API Freshwater Master Test Kit is the standard beginner choice: the cheap strip tests are not accurate enough for cycling). Do not skip this confirmation. Do not add fish. Do not add anything else. Just dose and wait. :INFO Step 3. Test daily and watch for the nitrite spike Starting from day two, test ammonia and nitrite every day. Record every reading: a simple notebook works fine. Week one to two: ammonia will begin to fall as Nitrosomonas bacteria establish and convert it to nitrite. Nitrite will climb from zero. Week two to four: the nitrite spike. This is the part that panics beginners. Nitrite will often hit 5 ppm or higher, and the test kit colour will go dark purple. This is normal. It simply means the first group of bacteria is working and the second group (Nitrobacter, which converts nitrite to nitrate) has not caught up yet. Do not do a water change to fix it. Do not panic. Wait. Keep the pH above 6.0 throughout. If it drops below that threshold, nitrifying bacteria stall. A 25 to 30 percent water change with dechlorinated water will recover the pH. :STATS [icon:FIRE] Ammonia: dose to | 2 to 4 ppm (re-dose when it drops to 0) [icon:CHART] Nitrite during spike | Often 5 ppm or more. Normal. Do not intervene. [icon:TARGET] Nitrate | Will climb steadily from week 2 onward. That is the cycle working. [icon:STAR] pH minimum | Above 6.0 (below this, bacteria stop working) :INFO Step 4. Re-dose ammonia throughout the cycle When ammonia drops to 0 or near 0, re-dose to 2 to 4 ppm. This keeps feeding the bacterial colony so it does not starve and crash. During the nitrite spike: add only half the initial ammonia dose every 2 to 3 days, and aim to keep nitrite under 5 ppm. Extremely high nitrite can slow the very bacteria that are supposed to clear it. After the nitrite spike falls: resume full doses of 2 to 4 ppm and test 24 hours later. You are now looking for the finish line. :INFO Step 5. Confirm the cycle is complete before adding fish The tank is fully cycled when you add 2 to 4 ppm of ammonia and BOTH ammonia and nitrite read 0 ppm within 24 hours, with nitrate present (typically 20 to 40 ppm). Confirm this result on 2 to 3 consecutive days before declaring victory. Nitrate itself is relatively harmless to fish in moderate amounts (under 40 ppm for community species). Before adding your first fish, do a 50 to 80 percent water change to knock the accumulated nitrate down to below 20 ppm. :STATS [icon:TARGET] Cycle complete when | Ammonia 0 ppm AND nitrite 0 ppm within 24h of a 2 to 4 ppm dose [icon:CHART] Nitrate before adding fish | Below 20 ppm (do a large water change to get there) [icon:CLOCK] Time with cold start | 4 to 6 weeks typical [icon:STAR] Time with bottled bacteria | 5 to 7 days (FritzZyme TurboStart 700 or Tetra SafeStart) :NOTE Add fish gradually once the tank is cycled. Introducing the full planned stock at once overwhelms the bacterial colony with ammonia it cannot yet process. Add one third of the fish, test for a week, then add more. :LINK https://www.drtimsaquatics.com/resources/fishless-cycling/ Dr. Tim's Aquatics: fishless cycling protocol (ammonia dosing, re-dose schedule, \ :LINK https://fishiverse.com/water-chemistry/cycling/ Fishiverse: freshwater cycling guide (step-by-step, completion criteria, timeline \