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Reef Tank Maintenance Schedule: Daily, Weekly & Monthly Checklist

A practical, frequency-based maintenance checklist for reef aquariums — from the five-minute daily glance to annual deep cleans. Compiled from the best practices of Bulk Reef Supply, Reef Builders, Top Shelf Aquatics, Reef2Reef, and the broader reef-keeping community.

12 min read Sources: 15 expert articles

1. Why Routine Maintenance Matters

A reef aquarium is a closed ecosystem. Unlike the ocean, which dilutes waste and replenishes trace elements across billions of litres, your tank relies entirely on you to maintain the chemical balance that keeps corals thriving. Routine maintenance is the single most important factor separating tanks that flourish from those that crash [1].

The goal is stability. Top Shelf Aquatics summarises the philosophy in three words: “Stability Promotes Success” [2]. Tanks where alkalinity varies less than ±0.3 dKH per day achieve 85–90% long-term coral survival, while tanks with ±1.0 dKH swings drop to 40–60% [2]. Consistency beats perfection every time.

Regular maintenance also lets you catch problems early. A daily five-minute walkthrough of your tank can reveal fish disease before it spreads, coral recession before it becomes tissue necrosis, or a failing pump before your sump overflows. By the time you notice a problem through water tests alone, the damage is often already done [3].

Key Principle: Little and often beats big and infrequent. Smaller, more frequent water changes and equipment cleanings cause less parameter shock than sporadic large interventions [4]. Build a routine you can actually stick to.

2. Daily Checklist (5 min)

Daily tasks are quick visual and sensory checks. They should take no more than five minutes and become second nature. BRS recommends treating this like a morning walk-by — observe, don’t intervene unless something looks wrong [1].

1

Visual Inspection

Scan all fish for signs of disease (white spots, rapid breathing, clamped fins, scratching). Check corals for normal polyp extension — retracted polyps or sudden colour change are early stress indicators [2]. Glance at flow patterns to ensure all powerheads are running.

2

Feed Your Tank

Feed fish and corals per your feeding schedule. Remove any uneaten food after 3–5 minutes to prevent nutrient spikes [5]. In SPS-dominant systems, target-feed corals sparingly — overfeeding drives nitrate and phosphate up quickly [3].

3

Check ATO (Auto Top-Off)

Verify the ATO reservoir has water and the float switch is free. A stuck float valve is one of the most common causes of salinity swings — either too much freshwater floods in or evaporation concentrates your salt [6]. Reef Builders notes salinity should stay within ±0.001 SG day to day [3].

4

Temperature Check

Glance at your thermometer or temperature controller. Reef tanks should hold 75–80°F (24–27°C) with less than 2°F daily swing [3]. Heater malfunctions (stuck on) are a leading cause of tank crashes — a controller with a high-temp cutoff is cheap insurance [2].

5

Equipment Spot-Check

Confirm the return pump, protein skimmer, and lights are operating normally. Listen for unusual noises from pumps. Check that the skimmer is producing foam — a dry cup or no foam can indicate an air-intake blockage [7].

SPS keepers: Top Shelf Aquatics recommends testing alkalinity daily during the first few weeks of a new system, then moving to 3x weekly once consumption patterns stabilise. Test at the same time each morning to capture overnight skeletal growth consumption [2].

3. Weekly Checklist (30 min)

Set aside 30 minutes once a week for these tasks. Many reefers pick a consistent day (e.g., Sunday morning) to build the habit [1].

1

Clean the Glass

Use a magnetic algae scraper or handheld pad to remove algae from viewing panels. Coralline algae on the back glass can be left — it’s beneficial. For acrylic tanks, use only acrylic-safe scrapers to avoid scratches [5].

2

Test Water Parameters

At minimum, test: salinity, temperature, nitrate (NO3), phosphate (PO4), alkalinity (dKH), calcium (Ca), and magnesium (Mg) [3] [8]. Record results in a log or app — trends matter more than single readings. Use reliable kits like Salifert or Hanna Checkers that provide 0.1 dKH resolution [2].

3

Clean Protein Skimmer Cup

Empty and rinse the collection cup. A dirty cup neck reduces skimming efficiency because the foam can’t climb a film-coated surface [7]. Rinse with hot freshwater (no soap) and wipe the neck interior.

4

Check & Replace Filter Socks

Swap dirty filter socks for clean ones. Clogged socks restrict flow and can become nitrate factories as trapped detritus decomposes [7]. Keep a rotation of 4–6 socks so you always have clean spares. Machine-wash used socks with bleach, then rinse thoroughly with freshwater and let dry [5].

5

Top Off ATO Reservoir

Refill with RO/DI water (0 TDS). If your TDS meter reads above 10 ppm, it’s time to replace your RO/DI filters [9]. A typical 50-gallon reef tank loses 1–2 gallons per day to evaporation depending on ambient humidity [6].

Don’t chase numbers. Reef Builders warns: “do not try to rush it, and do not chase numbers” [8]. If a parameter is slightly off but stable, leave it alone. Rapid corrections cause more damage than a steady, slightly off-target value.

4. Bi-Weekly Tasks

Every two weeks, schedule these deeper maintenance items. They take roughly 45–60 minutes combined.

1

10% Water Change

Prepare saltwater 24 hours ahead with RO/DI water, mix to 1.025 SG, and temperature-match within 2°F of tank water [9] [10]. Siphon old water from the sump while vacuuming detritus. Add new water slowly over 10–15 minutes. Red Sea recommends 10% weekly, with a maximum of 30% per single change [10]. Holmes-Farley notes that smaller changes more frequently is better than larger changes less often [4].

2

Clean Powerheads

Disassemble powerheads and wave makers and soak in a 50/50 white vinegar and water solution for 30–60 minutes. Scrub impellers and housings with a soft brush. Coralline algae and calcium deposits reduce flow output by up to 30% over time [7]. Rinse thoroughly with freshwater before reinstalling.

3

Dose Trace Elements

If your water changes alone don’t keep calcium, alkalinity, and magnesium stable, dose accordingly. Space alkalinity and calcium dosing 2–3 hours apart to prevent precipitation [2] [11]. Dose small amounts 3–4 times daily rather than one large dose for maximum stability [2].

4

Trim Macroalgae in Refugium

If you run a refugium with chaetomorpha or caulerpa, harvest excess growth. Overgrown macroalgae can go sexual (especially caulerpa), crash, and release nutrients back into the water [5]. Keep the mass to about half the refugium volume for optimal nutrient export.

5. Monthly Tasks

Monthly tasks involve deeper equipment maintenance. Block out 1–2 hours on a weekend [1].

1

Deep-Clean Protein Skimmer Body

Beyond the weekly cup rinse, disassemble the skimmer body, air intake, and venturi. Soak all parts in hot freshwater with white vinegar for 1–2 hours. Calcium and biofilm buildup inside the body and airline reduces air draw, cutting skimmate production significantly [7].

2

Replace Filter Media

Swap out activated carbon and GFO (granular ferric oxide) every 4–6 weeks. Exhausted carbon re-leaches absorbed organics back into the water, and spent GFO stops binding phosphate [7]. If running a media reactor, inspect tubing and pump flow rate during the swap.

3

Clean Return Pump

Pull the return pump, disassemble, and soak in citric acid or vinegar solution. Clear any debris from the impeller and volute. A return pump losing 20% flow from buildup means 20% less turnover in your display [7].

4

Calibrate Refractometer

Calibrate with a proper 35 ppt calibration solution (not distilled water, which doesn’t account for refractometer temperature compensation) [10]. A refractometer drifting by just 0.002 SG means your effective salinity is off by nearly 1 ppt — enough to stress sensitive SPS [2].

5

Inspect Heater

Check for cracks, discolouration, or corrosion on the heater tube. Verify the thermostat is reading accurately by comparing against an independent digital thermometer. Heater failures (stuck on or stuck off) are a leading cause of tank crashes [2]. Replace heaters proactively every 2–3 years.

Never do everything at once. Stagger deep cleans across different weeks. Cleaning the skimmer, replacing carbon, and doing a large water change on the same day can destabilise your bacterial populations and crash nutrient export [1].

6. Quarterly & Annual Tasks

These are the big-ticket maintenance items. Schedule them on a calendar so they don’t slip.

Quarterly (Every 3 Months)

  • Replace RO/DI sediment and carbon pre-filters. Most sediment filters last 3–6 months depending on source water quality. Check your TDS meter — if output exceeds 5 ppm, it’s time [9].
  • Deep-clean the sump. Siphon accumulated detritus from all sump chambers. Wipe down baffles and inspect silicone seals for leaks [7].
  • ICP-OES test your water. Send a sample to an ICP testing lab for a full 30+ element analysis. This catches trace element depletion or heavy metal contamination that home test kits cannot detect [3] [12].
  • Inspect plumbing and unions. Check all hose clamps, bulkheads, and union fittings for drips or salt creep. Tighten or replace gaskets as needed [7].

Annually (Every 12 Months)

  • Replace RO/DI membrane. DI resin and the RO membrane typically last 1–2 years. If your post-membrane TDS stays above 10% of input TDS, the membrane is failing [9].
  • Replace or inspect lighting. T5 bulbs lose significant spectrum output after 9–12 months and should be replaced. LED fixtures don’t degrade as quickly but should be inspected for failed diodes, dirty lenses, and fan operation [5].
  • Service or replace heaters. Heaters over 2–3 years old should be proactively replaced. Titanium heaters last longer but still need thermostat verification [2].
  • Full sump deep-clean. Drain, scrub, and inspect all sump chambers, baffles, and overflow boxes. Replace worn gaskets and check the overflow’s emergency drain path [7].
  • Review and replace dosing pump tubing. Peristaltic pump tubing stretches over time, changing flow rate. BRS recommends annual tubing replacement and re-calibration [1].

7. Water Testing Schedule

How often you test depends on your tank’s maturity and coral load. Reef Builders recommends testing ammonia and nitrite 3+ times per week in new tanks until the nitrogen cycle completes, then transitioning to a stable weekly schedule [3]. Target ranges compiled from Reef Builders [3], Top Shelf Aquatics [2], and Reef Chasers [8]:

Parameter Target Range New Tank Established (Soft/LPS) Established (SPS) Source
Temperature 75–80°F Daily Daily (glance) Daily (glance) [3]
Salinity (SG) 1.024–1.026 Daily Weekly 2–3x/week [3]
Ammonia (NH3) 0 ppm 3x/week Monthly Monthly [3]
Nitrite (NO2) 0 ppm 3x/week Monthly Monthly [3]
Nitrate (NO3) 1–10 ppm Weekly Weekly Weekly [3]
Phosphate (PO4) 0.01–0.10 ppm Weekly Weekly Weekly [3]
Alkalinity (dKH) 7.5–10 dKH 2–3x/week Weekly 3x/week (daily at start) [2] [8]
Calcium (Ca) 400–450 ppm Weekly Weekly Weekly [3] [8]
Magnesium (Mg) 1,250–1,400 ppm Weekly Bi-weekly Weekly [2] [8]
pH 8.0–8.3 Weekly Monthly Weekly [8]
Pro tip: Invest in quality test kits. Cheap kits with poor resolution make effective monitoring impossible [2]. Hanna Checkers for alkalinity and phosphate, and Salifert for calcium and magnesium, are the community gold standard.

8. Maintenance Tools & Supplies

Keep these tools organised and ready so maintenance doesn’t become a chore. Based on recommendations from BRS [1] and the Reef2Reef community [6]:

Cleaning Tools

  • Magnetic algae scraper (Flipper or Tunze) [5]
  • Turkey baster — for blasting detritus off rocks and corals [5]
  • Gravel vacuum / siphon hose [7]
  • Soft-bristle brushes (for pump impellers) [7]
  • 5-gallon HDPE buckets (dedicated to saltwater only) [9]
  • Towels and a drip tray (prevents salt creep on floors)

Testing & Consumables

  • Hanna Checkers (alkalinity HI772, phosphate HI713) [2]
  • Salifert or Red Sea test kits (Ca, Mg, NO3) [2]
  • Refractometer + 35 ppt calibration fluid [10]
  • TDS meter (for RO/DI output verification) [9]
  • Replacement filter socks (4–6 in rotation) [7]
  • Activated carbon & GFO (monthly replacement) [7]
  • White vinegar or citric acid (for equipment soaking)
  • Spare RO/DI sediment, carbon, and DI resin cartridges [9]
Organisation tip: Keep a “maintenance kit” caddy near your tank with scraper, turkey baster, test kits, and towels. The lower the friction to start, the more consistently you’ll do it.

9. Frequently Asked Questions

How often should I do water changes on a reef tank?

10% every one to two weeks is the gold standard for reef tanks [10] [4]. Holmes-Farley recommends 15–30% monthly as an alternative [4]. The universal principle: smaller changes more often beats larger changes less often. Never exceed 30% in a single change [10].

What is the most important parameter to keep stable?

Alkalinity, followed by temperature and calcium. Top Shelf Aquatics ranks the stability priority as: alkalinity → temperature → calcium → salinity → magnesium → pH [2]. Daily alkalinity variation should stay under 0.3 dKH for SPS, and under 0.5 dKH maximum [2] [8].

How do I know if my protein skimmer needs cleaning?

If the collection cup isn’t producing dark, tea-coloured skimmate, or if foam fails to rise above the cup neck, the skimmer needs attention. Clean the cup neck weekly and deep-clean the entire body (including the venturi and air intake) monthly [7]. Calcium deposits and biofilm reduce air draw and foam production.

When should I replace my RO/DI filters?

Replace sediment and carbon pre-filters every 3–6 months, and the RO membrane every 1–2 years. Monitor with a TDS meter: if output exceeds 5–10 ppm, filters are exhausted [9]. DI resin changes colour when spent. Source water quality (chloramine, high TDS) shortens filter life significantly.

Can I skip water changes if I dose trace elements?

Some advanced reefers run ultra-low-nutrient systems with minimal water changes, relying on dosing and ICP testing. However, for most hobbyists, water changes serve purposes beyond element replenishment — they export dissolved organics, dilute accumulated pollutants, and replenish minor and trace elements that are difficult to dose individually [4] [12]. Regular water changes remain the safest approach.

How often should I run an ICP test?

Every 3–4 months for established reef tanks, or immediately if you notice unexplained coral stress. ICP-OES analysis tests 30+ elements that home kits cannot measure, revealing heavy metal contamination, trace element depletion, or dosing imbalances [3] [12]. Always test both your tank water and your freshly mixed saltwater to isolate the source of any anomalies.

References

Every factual claim in this guide is cited to its original source. Click any [n] in the text above to jump here.

  1. Bulk Reef Supply — “5 Minute Saltwater Aquarium Guide: Maintenance Schedule”
  2. Top Shelf Aquatics — “SPS Coral Stability: The Complete Guide to Maintaining Consistent Parameters”
  3. Reef Builders — “Important Water Parameters For Keeping A Saltwater Aquarium” (2020)
  4. Randy Holmes-Farley — “Water Changes in Reef Aquaria” (Reefkeeping Magazine, 2005)
  5. Reef2Reef — “Reef Tank Maintenance & Water Change FAQ”
  6. Reef2Reef — Community maintenance schedule threads
  7. Melev’s Reef — “How to Mix & Change Saltwater Correctly” (equipment maintenance tips)
  8. Reef Chasers — “Alkalinity, Calcium, and Your Reef Tank”
  9. Bulk Reef Supply — “RO/DI Water Filter Maintenance Guide”
  10. Red Sea — “How to Mix Perfect Saltwater — Tips & Tricks”
  11. Reefs.com — “Aquarium Chemistry: Magnesium In Reef Aquaria”
  12. Reef Builders — “The Importance of Calcium, Alkalinity, and Magnesium in a Reef Tank” (2023)
  13. Bulk Reef Supply — “Reef Tank Maintenance: The Complete Schedule”
  14. Reef Builders — “How to Select a Reef Salt” (2023)
  15. Aquarium Store Depot — “The 7 Best Reef Salt Mixes — Reviewed And Tested”

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