By AquaMart Staff

How to Cycle your New Reef Tank

Cycling a reef aquarium establishes beneficial bacteria that convert toxic ammonia into nitrite and then into nitrate, creating a stable and safe environment for marine life. Here's a step-by-step guide to properly cycle your reef tank:

Step-by-Step Process to Cycle a Reef Tank

  1. Set Up the Aquarium
  • Install Equipment:
    • Heater, return pump, skimmer (can be turned off during initial cycling), powerheads, and lights.
  • Add Substrate: Use live sand or dry aragonite sand.
  • Add Rock: Choose live rock (contains bacteria) or dry rock (will become live over time).
    • Live rock can speed up the cycle. Dry rock takes longer but avoids unwanted hitchhikers.
  • Mix Saltwater:
    • Use RO/DI water with high-quality reef salt and test for proper salinity (1.024–1.026 SG).
  1. Introduce an Ammonia Source

The goal is to establish a population of nitrifying bacteria by providing an ammonia source. You can do this in several ways:

  • Add Fishless Ammonia: Use pure ammonia (without surfactants) to raise the level to 2-3 ppm.
  • Ghost Feeding: Add a small amount of fish food to the tank and let it decay.
  • Live Rock or Live Sand: These already contain bacteria and can jump-start the cycle.
  • Bacterial Starter Products: Products like Dr. Tim's One & Only or Bio-Spira introduce beneficial bacteria directly.
  1. Test Water Parameters Regularly

Throughout the cycle, you need to monitor key parameters with test kits:

  • Ammonia (NH₃/NH₄⁺): Toxic to fish; should initially rise, then drop to 0 ppm.
  • Nitrite (NO₂⁻): Intermediate product; toxic but will eventually drop to 0 ppm.
  • Nitrate (NO₃⁻): Final product; safe in low concentrations.
    • Goal: Ammonia and nitrite should read 0 ppm while nitrate may rise.
  • Testing Schedule:
    • Test every 2–3 days to track the progress of the cycle.
  1. Watch for Bacteria Growth Phases
  • Phase 1: Ammonia Spike (2–5 ppm)
    • Beneficial bacteria start colonizing and begin converting ammonia to nitrite.
  • Phase 2: Nitrite Spike
    • As nitrites rise, ammonia starts to decline. Nitrite will eventually be converted into nitrate.
  • Phase 3: Nitrates Accumulate
    • When both ammonia and nitrite are at 0 ppm and nitrates are present, the cycle is complete.
  1. Perform a Water Change (Optional)

Once the cycle is complete (0 ammonia and nitrite), perform a 10–20% water change to lower nitrate levels.

  • Target Nitrate Level: Below 10 ppm for reef systems.
  1. Add Clean-Up Crew (Optional)
  • Introduce a small clean-up crew (e.g., snails, hermit crabs) to help control algae growth as the tank matures.
  1. Add Fish Slowly
  • Start with a hardy fish (like a clownfish) and only add one or two fish at a time.
  • Test water parameters after adding new livestock to ensure ammonia remains at 0 ppm.
  1. Use Lights Sparingly During the Cycle
  • Limit lighting to prevent algae outbreaks, as the tank is vulnerable to nuisance algae during the early stages.
  • Once the cycle is complete, gradually increase the lighting schedule for corals.
  1. Be Patient – The Process Takes Time
  • Dry Rock: May take 4–8 weeks to fully cycle.
  • Live Rock: May cycle in 2–4 weeks or less.

Signs That the Cycle is Complete

  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: >0 ppm (can be reduced with water changes)
  • The tank is now ready for gradual livestock introduction.

Optional: Seed the Tank with Bacteria

  • Products like Turbo Start, Dr. Tim’s One & Only, or MicroBacter7 can accelerate the cycling process.

Prevent Future Problems

  • Quarantine new fish and corals to avoid introducing pests or diseases.
  • Continue water testing weekly to catch any fluctuations in parameters.

With patience and consistent monitoring, your reef tank will successfully cycle, providing a healthy environment for fish, corals, and invertebrates!

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