How to cycle a saltwater tank, how long it takes, and surviving the "ugly stage" before you add livestock.
5 questions, answered honestly and water-first.
Add an ammonia source (bottled ammonia, or let live rock do it) and let the bacteria build until the tank turns a dose of ammonia into zero ammonia and zero nitrite within 24 hours, with nitrate appearing. Test, don't guess — and add no livestock until it's done. Live rock or seeded media speeds it up.
Usually 2–6 weeks. The calendar doesn't decide it — the water does: it's cycled when a dose of ammonia clears to zero ammonia and zero nitrite within a day, and you're reading nitrate. Seeding with mature live rock or filter media can shorten it considerably.
Please don't. Fish-in cycling is stressful and often fatal, and damsels are aggressive and notoriously hard to catch out later once your rock is aquascaped. Cycle fishless with an ammonia source — it's kinder, easier, and lets you build the tank properly first.
A young tank goes through blooms of diatoms (brown dust) and other algae as it matures and finds its balance — it's normal and temporary, not a failure. Ride it out with patience, good flow and light nutrient control rather than nuking it. A cleanup crew helps once the tank is a little more settled.
Add a hardy fish or two only after the cycle finishes and parameters are stable, then stock slowly. Corals come later, once the tank has matured over weeks to months — start with soft corals and easy LPS, and leave SPS until the tank is well-established.
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Short answers from the Coralkin team — kind, general guidance, not a diagnosis. When something looks wrong, test your water first, and for a serious case ask an experienced reefer or an aquatic vet.
