How to Tank Cycling for Reef Keeping - Step by Step
Step-by-step guide to Tank Cycling for Reef Keeping. Includes time estimates, tips, and common mistakes to avoid.
Track your tank cycling schedule and history in one place. Free.
Start logging freeCycling a reef tank is the process of building a stable population of beneficial bacteria that convert toxic ammonia into nitrite and then nitrate before fish, corals, or invertebrates are added. A careful, measured cycle helps prevent livestock loss, limits ugly early-stage algae outbreaks, and gives your reef a much stronger start.
Prerequisites
- -Aquarium, stand, sump or filtration system, and return pump fully installed and leak tested
- -RODI water and a quality reef salt mix to prepare saltwater at 1.025-1.026 SG
- -Refractometer or calibrated digital salinity meter
- -Heater and thermometer to maintain 77-79 F
- -Flow pumps or wavemakers for internal circulation
- -Dry rock, live rock, or a combination, plus rinsed reef-safe sand if using a sand bed
- -Reliable test kits for ammonia, nitrite, nitrate, pH, alkalinity, and phosphate
- -A bottled nitrifying bacteria product rated for saltwater systems
- -A measured ammonia source such as ammonium chloride or a small amount of fish food
- -Basic understanding of the nitrogen cycle and how to interpret ppm-based test results
Fill the tank and sump with RODI water, add reef salt, and circulate it for at least 24 hours before beginning the cycle. Adjust salinity to 1.025-1.026 SG and stabilize temperature at 77-79 F. Confirm pH is roughly 7.9-8.3 and ensure all pumps, heater, and overflow are running correctly.
Tips
- +Mix salt in a brute container or reservoir first if possible, then transfer to the display for more consistent salinity
- +Calibrate your refractometer with calibration fluid, not freshwater
Common Mistakes
- -Starting the cycle with unstable salinity or temperature
- -Using untreated tap water, which can introduce phosphate, silicate, and other contaminants
Pro Tips
- *If you start with true ocean-cultured live rock, inspect carefully for pests like aiptasia, mantis shrimp, and nuisance crabs before placing it in the display
- *For dry rock systems, consider ghost feeding lightly after the cycle if livestock will not be added right away, so the bacterial population does not shrink
- *Keep alkalinity in a reasonable range during startup, around 7.5-9.0 dKH, because extreme values can add unnecessary instability while the tank matures
- *Do not rely on nitrate alone to judge cycle completion, because nitrate can appear before the tank can consistently process a fresh ammonia input
- *When the cycle is complete, add livestock in stages at least 1-2 weeks apart so the biological filter can scale up safely with each increase in bioload
Keep a clean backup log for test day.
The Printable Reef Logbook gives you water testing, dosing, maintenance, and livestock worksheets you can print or save as a PDF.