The Complete Reef Maintenance Schedule (Daily to Yearly)

A reef tank almost never dies of catastrophe. It dies of drift — alkalinity that slid a little further every week, a heater that stuck a degree high in June, detritus that accumulated quietly until nitrate crossed 40 ppm and the acropora browned out. A maintenance schedule exists to catch drift while it is still cheap to correct. The frustrating part is that skipping any single task has no visible consequence, which is exactly why schedules erode. This calendar covers everything from the two-minute daily glance to the yearly equipment overhaul, with honest time estimates and an explanation of what each task actually protects.

If you are still assembling your first system, our free ebook The First Tank walks through the equipment this schedule assumes: a heater, decent flow, basic test kits, and a reliable source of RO/DI water. Everything below scales from a 20-gallon nano to a 200-gallon mixed reef — only the volumes change.

Daily: the two-minute look

The most valuable maintenance tool you own is your own attention at feeding time. Every day, before you drop food in:

• Count your fish and watch how they swim. A fish hiding at feeding time is your earliest disease warning.
• Read polyp extension. Corals close in response to chemistry problems days before a test kit will show you anything. If the hammer that is always open is suddenly sulking, test tonight, not this weekend.
• Check the temperature display against what it usually reads, and glance at the auto top-off reservoir and sump water level.
• Look at the skimmer. A skimmer that suddenly goes wild or goes flat is telling you something changed in the water.

Then feed. Total time: two to five minutes. This habit catches more problems than every test kit you own combined.

Weekly: testing and the water change (45–60 minutes)

Once a week, on the same day if you can manage it:

Test alkalinity and salinity. Alkalinity is the single most consumption-sensitive parameter in a reef, and it moves fast enough that weekly testing is the minimum once you keep stony corals. A titration-style alkalinity test kit takes about three minutes. If your number is falling week over week, read why alkalinity drops before you chase it — the cause is almost always coral growth, and the fix is dosing, not panic.

Do the water change. For most tanks, 10 percent weekly is the sweet spot: enough to export nutrients and replenish trace elements, small enough that nothing swings. Mix your reef salt mix with RO/DI water, match temperature and salinity to the tank, and siphon from the sand bed or rock crevices where detritus settles. We cover the reasoning and the exceptions in how often to change water in a reef tank.

Clean the glass. Film algae builds daily; a magnetic algae scraper makes this a thirty-second job instead of a wet-arm session. Do it before the water change so the debris gets exported.

Swap filter socks or floss and empty the skimmer cup. Mechanical filtration only exports waste if you remove it before it decomposes — a sock left in for two weeks is a nitrate factory, not a filter.

Baste the rockwork. A turkey baster or small powerhead blast across the rock puts settled detritus into the water column right before you siphon. Thirty seconds, big payoff.

Every two weeks: the full parameter panel (20 minutes)

Alkalinity weekly; everything else biweekly is enough for a stable tank. Test calcium, magnesium, nitrate, and phosphate, and log the numbers — a single reading means little, but six weeks of readings show you the trend line, and trends are what you actually manage. Our reef tank parameters chart lists the target ranges. If you want to understand why those ranges matter and how the major elements interact, the Reef Chemistry Handbook is the deep version — it will save you from most of the corrective dosing mistakes that sink second-year reefers.

Monthly: the equipment touch (30–45 minutes)

Equipment fails slowly before it fails suddenly. Once a month:

• Deep-clean the skimmer cup and neck. A slick neck skims noticeably wetter and pulls more waste.
• Clean pump intakes and wavemaker cages. Algae and sponge growth choke flow gradually — you rarely notice until you clean one and see the difference.
• Calibrate the refractometer with 35 ppt calibration fluid. An uncalibrated refractometer is the most common source of salinity drift we see.
• Replace chemical media — carbon and GFO exhaust silently and then simply stop working.
• Inspect the heater for cracked housing or salt creep at the cord, and confirm the controller setpoint matches the thermometer.
• Check dosing containers and tubing for level, air locks, and kinks.

Quarterly: the deep service (1–2 hours)

Every three months, pick a weekend:

• Vinegar-soak the return pump, skimmer pump, and wavemakers. Calcium deposits on impellers cut output and shorten motor life. A one-hour soak in 1:1 vinegar and water restores them.
• Check RO/DI performance. If your TDS meter reads above zero after the DI stage, replace the resin.
• Send an ICP water test. Hobby kits cover the big six; a mail-in ICP test catches trace element depletion and contamination — tin, copper, iodine — that you cannot test at home.
• Clean light lenses and fans. Salt spray on a lens can cost you 10–20 percent of your PAR without any visible change.
• Inspect plumbing, unions, and valves for salt creep and weeping joints.

Yearly: replace before failure

Some equipment should be retired on schedule, not on death, because its failure mode takes the tank with it:

• Heaters are the classic tank killer. Replace cheap ones yearly; even quality heaters deserve replacement every two years and an external controller for the whole of their life.
• Dosing pump tubing hardens and slips. Replace it annually and recalibrate.
• RO membranes and prefilters per your TDS readings and usage.
• Impellers and shafts on pumps showing noise or reduced output.

The yearly mark is also when most reefs need editorial work: colonies that have grown into each other, zoas swallowing a rock, a torch declaring war on its neighbors. Pruning and fragging is genuinely enjoyable once you have done it a few times — Coral Care and Propagation covers the tools and technique, and the frags become trade credit at your local fish store.

Keep a log, even a lazy one

A notebook, a spreadsheet, a notes app — it does not matter. Write down test results, dosing changes, livestock additions, and equipment swaps with dates. When something goes wrong (and something eventually will), the log is the difference between diagnosing the cause in ten minutes and guessing for three weeks. Every experienced reefer who sounds psychic about tank problems is really just reading their own records.

FAQ

What happens if I miss a week?

Almost nothing — once. A healthy reef has enormous inertia, and that is precisely the trap. One missed week becomes three, alkalinity drifts, nutrients climb, and the tank that "was fine without maintenance" crashes two months later. Miss a week guiltlessly, then get back on schedule.

Do I still need water changes if I dose two-part?

Yes, though arguably fewer. Dosing replaces alkalinity and calcium, but water changes also export nutrients and organics while replenishing dozens of trace elements no two-part contains. Most successful dosed tanks still change 10 percent every one to two weeks.

How much total time does this schedule take?

Roughly one hour a week for a mid-size tank, plus a longer session quarterly. Reefers who spend more time than that are usually doing something wrong; reefers who spend much less usually will be.