Aquarium · Reef & saltwater
Reef tank live rock curing timeline calculator
Live rock arrives covered in organisms that don't survive the trip out of water, and as that dead material decomposes it dumps a serious ammonia and nitrite load into a new tank. Curing is the process of letting that die-off finish and your bacteria colony catch up before the rock goes into a display tank with fish or coral on it. Skip curing and you're effectively starting a nitrogen cycle in a tank you thought was already stocked, which is a common way reef keepers lose their first round of livestock.
Estimated curing window
14–56 days
- Fresh rock can smell strongly and cloud the water for the first several days. That's normal, keep the lights off and don't add anything else to the tank yet.
- The calendar is a starting estimate. The rock is actually cured when ammonia and nitrite read zero on two tests a couple of days apart, not on a fixed day.
What to actually buy
API Saltwater Master Test Kit
Curing is only done when ammonia and nitrite actually test at zero, not when the calendar says so. This is the standard saltwater equivalent of the freshwater kit, covering the parameters that actually matter during curing.
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How this is calculated
The starting range comes from how much dying organic matter is on the rock. Store-bought or second-hand rock that's already established usually clears in a few days to two weeks. Dry base rock seeded with a bit of live rock takes one to five weeks. Fresh rock straight from the ocean has the most die-off and typically needs two to eight weeks before ammonia and nitrite settle at zero.
Temperature gets a modest adjustment on top of that. Warmer water (80-82°F) speeds up decomposition and the bacteria breaking it down, so curing tends to finish faster. Cooler water slows both down. This adjustment is intentionally conservative since the underlying sources describe the temperature effect qualitatively rather than with a precise curve, unlike the more established math behind the nitrogen cycle calculator.
The calendar estimate is a starting point, not a finish line. The rock is actually cured when a liquid test kit reads zero ammonia and zero nitrite two tests in a row, a couple of days apart.
Frequently asked questions
How do I know curing is actually done?
Test, don't guess. Curing is finished when a liquid test kit reads zero ammonia and zero nitrite on two tests a couple of days apart. The date range this calculator gives you is a planning window for scheduling water changes and buying equipment, not a substitute for testing before you add anything living.
Should I do water changes during curing?
Yes, and often. Frequent partial water changes during curing dilute the ammonia and nitrite spikes and physically remove the decomposing organic matter causing them, which shortens the overall process compared to leaving the water alone and just waiting.
Can I speed up curing with more flow or a protein skimmer?
Both help. Strong flow keeps decomposing debris in suspension so it gets exported instead of settling into rock crevices and rotting slowly, and a protein skimmer pulls dissolved organics out of the water column before they finish decomposing into ammonia. Neither one replaces the temperature and water change effects this calculator already accounts for, but a well-flowed, skimmed curing tank tends to land at the faster end of its estimated range.
Is dry base rock less work than wet live rock?
It's less risky, not necessarily less work. Dry rock has no die-off to cure since nothing on it was ever alive, but it also has none of the beneficial bacteria and diversity live rock brings, so it needs to be seeded with a smaller amount of real live rock or bottled bacteria and then cycled like a bare tank, which is what the shorter end of this calculator's dry-rock range reflects.