Aquarium Maintenance Log (Weekly)
An aquarium weekly maintenance log — tank setup (size, type, stock), test results (temp, pH, ammonia, nitrite, nitrate, salinity for SW), water change %, equipment checks, observations.
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AQUARIUM WEEKLY MAINTENANCE LOG Tank: Living Room 75-gal Planted Community Type: freshwater Volume: 75 gal (display) · 90 gal total with sump Stock: 8x cardinal tetra, 6x corydoras sterbai, 2x angelfish, 1x bristlenose pleco, 12x amano shrimp Plants/corals: Anubias, java fern, vallisneria, dwarf chain sword, red root floaters Log date: June 15, 2026 WATER TEST RESULTS Temperature: 78.2 °F (target 76-80 FW / 76-80 SW) pH: 7.0 (target 6.5-7.5 FW / 8.1-8.4 SW) Ammonia (NH3): 0.0 ppm (target 0) Nitrite (NO2): 0.0 ppm (target 0) Nitrate (NO3): 10 ppm (target <20 FW / <10 SW) Salinity (SG): n/a (freshwater) (target 1.024-1.026 reef) Hardness: GH 7 · KH 4 WATER CHANGE 25% (~22 gal) RO/DI re-mineralized to GH 7 / KH 4, temperature-matched FILTER / EQUIPMENT Rinsed sponge stage 1 of canister in old tank water; impeller spinning freely; heater set to 78°F (reading 78.2); CO2 BPS 2/sec. OBSERVATIONS / BEHAVIOR All fish active + eating; angelfish pair displaying spawning behavior; cardinal tetra colors strong; bristlenose grazing; shrimp molting (one fresh molt on substrate). No algae outbreak this week; light spot on driftwood = beneficial biofilm. FEEDING (this week) Daily: micropellets AM + frozen bloodworms or daphnia PM. Sundays: fasting day. Plants/wood for grazers throughout. WEEKLY CHECKLIST [ ] Water tested + recorded above [ ] Water change performed (target 10-25% weekly) [ ] Filter sponge / sock checked (rinse in tank water; do NOT use tap) [ ] Heater + thermometer match [ ] Lights working + on schedule [ ] Top-off water ready for the week (FW) or auto-top-off OK (SW) [ ] Algae spot-clean (glass scraper, no harsh chemicals) [ ] Test kit reagents within expiration [ ] All livestock counted + observed eating [ ] Photos of tank + any new growth / concern
About this template
An **aquarium is a slow chemistry experiment that the fish are living in**, and the weekly log is the evidence that the chemistry is staying inside its safe window. Five tests carry the load: **ammonia (NH3)** and **nitrite (NO2)** must be **0 ppm** in a cycled tank (any reading means the biological filter is impaired and the livestock are being poisoned), **nitrate (NO3)** below ~20 ppm in freshwater and below ~10 ppm in reef (high nitrate is a slower poison, an algae trigger, and a stress factor for coral), **pH** stable inside the range appropriate to the stock (most FW 6.5-7.5, African cichlid 7.8-8.4, marine reef 8.1-8.4), and **salinity** (SG 1.024-1.026 for reef, 1.020-1.025 for FOWLR). Once the cycle is established the log becomes a **trend monitor** — the failure pattern is rarely a single bad reading; it is a creeping nitrate, a drifting pH, a temperature swing nobody noticed. **Water changes** are the single highest-value weekly action — 10-25% of volume, dechlorinated (or RO/DI re-mineralized), temperature-matched within 2°F, and not done the same day as filter maintenance (cleaning the biofilter the same day as a big water change can crash a delicate tank). Use **old tank water** to rinse mechanical filter media — tap water kills the beneficial bacteria. **Salt mixes** for reef have to be matched to a precise refractometer reading; conductivity is the test, not "scoop and pour." **Lighting schedule** matters more than most beginners think — too long a photoperiod (>10 hours) creates algae problems even on a low-light setup. **Equipment checks** belong on the log: heater reading vs. thermometer reading, return pump flow, skimmer collection (reef), top-off water present. **Stock observations** are the diagnostic: a fish off feed, hiding more than usual, breathing fast, or with new white spots / fungus / fin rot is a vet question, not a "wait a week" question. **Cycle the tank before adding livestock** (fishless ammonia cycle takes 4-6 weeks); the log starts at week 1 of the cycle, with daily testing during the cycle and weekly testing thereafter. **Quarantine** new fish for 4 weeks in a separate hospital tank to avoid importing disease into a stable display. Save the logs — six months of weekly data is the diagnostic chart a fish vet asks for first.
When to use it
- Weekly home-aquarium maintenance routine.
- Hand-off log for a fish-sitter during vacation.
- Diagnostic record when livestock show illness.
- Pre-purchase record for a high-value tank or stock.
- Reef-tank operator tracking salinity + alk + Ca + Mg trends.
What to include
- Tank metadata (size, type, stock, plants/corals).
- Test results: temp, pH, ammonia, nitrite, nitrate, salinity if SW, hardness.
- Water change percentage + source.
- Filter + equipment service done this week.
- Stock observations + behavior.
- Feeding schedule.
- Weekly checklist.