Look, then test
Test before the water change so results show how the tank is really doing.
- Note closed corals, new algae, pests or missing fish
- Test salinity and alkalinity, plus any tests due
- Write each result next to the date
Reef care
Weekly Reef Routine
A reef stays healthy through small, steady habits. Look the tank over every day, test the numbers that move fastest each week, and change water with saltwater that already matches the tank. Most reef trouble starts with a swing, not one bad number.
At a glance
Daily, weekly, monthly
A starting schedule. Tanks with many stony corals, or tanks you dose, need closer testing.
| Task | Why it matters |
|---|---|
| Every day | |
| Look over fish, corals and equipment | Two minutes catches a closed coral, a missing fish, a stopped pump or a drip early. |
| Check temperature and top-off water | Steady matters more than exact (many reefs run about 76-80°F). Salt stays behind when water evaporates, so salinity climbs if top-off runs out. |
| Every week (or two) | |
| Test salinity and alkalinity | These move fastest. Typical targets: salinity about 1.025-1.026 SG (35 ppt), alkalinity about 7-11 dKH and held steady. Test more often if you dose. |
| Water change with pre-mixed saltwater | Dilutes nitrate, phosphate and waste, and replaces some of what corals use. Many reefers change about 10-20% every one to two weeks. |
| Empty the skimmer cup, change filter socks | Trapped waste keeps breaking down until it leaves. Do this every few days to weekly. On a fleece roller, check the roll and sensor. |
| Clean the glass | As needed. Keeps light reaching corals and makes pests easier to spot. |
| Every two to four weeks | |
| Test calcium, magnesium, nitrate and phosphate | Slower movers. Typical targets: calcium about 380-450 ppm, magnesium about 1250-1400 ppm. Watch nitrate and phosphate trends; very high and bottomed-out readings both cause trouble. |
| Check the refractometer | Use 35 ppt calibration fluid. A drifting refractometer is wrong every time you use it. |
| Wipe salt creep, check RO/DI water | Salt creep damages lights and cords. A TDS meter shows when DI resin is spent. |
| Every few months | |
| Clean pumps, wavemakers and the skimmer | Mineral buildup slowly chokes flow. Soak parts in vinegar and water or an aquarium pump cleaner, then rinse well. |
Weekly routine
Do these in order
Test first, do the messy jobs next, then change water so loosened debris leaves the tank.
Clean glass and filters
Do this first so the loosened debris gets siphoned out.
- Clean the glass and let debris settle
- Empty and rinse the skimmer cup
- Swap dirty filter socks for clean ones
Change the water
Use saltwater mixed ahead with RO/DI water and fully dissolved. Never add salt mix straight to the tank.
- Turn off the auto top-off, and the return pump on sump tanks
- Unplug heaters that could end up out of the water
- Match salinity and temperature, then refill slowly
Restart and top off
Confirm everything runs before you walk away.
- Turn pumps, heaters, skimmer and top-off back on
- Top off with fresh RO/DI water only, never saltwater
- Check later; skimmers can overflow after a change
What you need
Keep a reef kit ready
Keep aquarium tools separate. Soap and household sprays do not belong near a reef.
Refractometer and kits
- Refractometer and calibration fluid
- Alkalinity, calcium and magnesium tests
- Nitrate and phosphate tests, thermometer
RO/DI and salt mix
- RO/DI water and reef salt mix
- Mixing container with heater and pump
- Top-off reservoir
Glass and siphon tools
- Magnet or scraper rated for your tank
- Siphon hose and aquarium-only buckets
- Towels for drips and salt creep
Filter and pump care
- Spare filter socks or fleece roll
- Brushes for the skimmer neck and pumps
- Small tub for soaking pumps
Common mistakes
Keep the tank boring
Corals handle a steady, slightly imperfect number better than a fast swing toward a perfect one. Change one thing at a time and give the tank a few days to respond.
- Topping off with saltwater. Salt does not evaporate, so salinity creeps up.
- Leaving the top-off on during a water change. It fills the gap with freshwater.
- Using new saltwater that is not ready. Cloudy, cold or mismatched water stresses corals.
- Forgetting to restart pumps or heaters. Set a phone timer before you start.
- Leaving filter socks until they overflow. Water bypasses the sock and waste stays in.
- Fixing a low number all at once. Alkalinity should change less than about 1 dKH a day.