Extended absence: keeping your aquarium alive

Leaving for a week with anxiety about the tank is a classic story. In reality, with the right prep, an aquarium goes without its owner longer than most people think. The key: prepare ahead and don't panic.

Duration scenarios

1–3 days

Do nothing. Healthy fish go 3 days without food easily — it's shorter than a natural feeding gap. Far better to under-feed than to dump 'extra' food on the way out.

4–7 days

The day before, do a 30 % water change so starting nitrates are minimal. Set the light timer to 6 hours per day (shorter than usual to lower biofilter load). For food — a single mid-trip feeding (e.g. a slow-release gel block) is plenty.

8–14 days

Minimum: an auto-feeder plus a neighbour or friend who glances in every 4–5 days. Their job: check the filter is running, temperature is normal, fish are swimming. No 'extra topping up' of food.

15+ days

A responsible 'sitter' is required: a 30 % water change every 10 days, supervision of the auto-feeder. Best — another fishkeeper or a relative trained beforehand. Without anyone, fish can survive 3 weeks but nitrate buildup damages long-term health.

'Week before' checklist

• 30 % water change one day before departure. • Filter rinse in tank water. • Heater and thermometer check (a backup thermometer is mandatory). • Replace fluorescent tubes if older than 10 months. • Set light timers to the reduced schedule (6 h instead of 8). • Full test kit (NH₃, NO₂, NO₃, pH) — replace any expired bottles. • Water conditioner (Prime/AquaSafe), spare nets, spare thermometer — leave with helper.

Auto-feeders

A real lifesaver for trips up to 2 weeks. • Drum (rotary) — one turn per day, drops a portion. The most reliable. • Auger — continuous dispensing on a schedule. Good for multi-feed routines. • Gel blocks — dissolve over 4–7 days. A last-resort option. Key rule: run the feeder for 3 days before leaving to confirm dosing and that it doesn't jam.

Sitter brief

Print a one-page sheet and leave it visible: 1. Every 4–5 days — look at the tank for 1 minute. 2. If all fish swim normally — do nothing. 3. If anyone is sideways, glued to glass, or gasping at the surface — call. 4. If the filter is noisy or off — call, don't try to fix. 5. Feed ONLY if the auto-feeder is nearly empty (after 8+ days).

What to leave the helper

• Food container clearly labelled ('one pinch into the feeder'). • Water conditioner (Prime) — 30 ml. • A backup heater in its box (in case the current one fails). • 5 L of conditioned water in a canister (in case of any leak). • Phone numbers: yours + a fellow fishkeeper for advice.

What to switch off

• Auto-doser for fertilisers — plants survive 2 weeks without dosing. An overdose with no one around is more dangerous than the gap. • CO₂ — a regulator misfire can poison the fish in 24 hours. • Auxiliary pumps / cooling fans that aren't part of the core filtration loop.

When you come back

• Don't do a water change right away — the parameters have stabilised, don't shock them with new water. • Watch for 24 hours: all fish present, no algae outbreak, no smell of rot. • Run the full test kit. • Next day — 30 % water change and a light feed.

Worst cases and defences

• Power outage: a UPS sized for 4–6 hours of filter runtime (server UPS, ~$80). Without flow, bacteria die. • Heater failure: backup heater + temperature-cutoff thermostat plug. • Burst canister hose: a tray under the filter + a leak sensor that pings your phone.

An aquarium goes without you better than you fear — if you spend a careful day preparing before you leave. The worst thing is when people 'feed it like themselves' instead of like a fish.