Maintenance

Maintenance is the part of the hobby nobody posts on Instagram. It is also the part that decides whether your fish live for two years or ten. The single biggest predictor of a stable tank is not the filter, not the lights, not the species — it is whether the aquarist shows up every week to do the work. The guides in this section cover the routines, the techniques, and the reasoning behind each task, so you can do them well rather than just often.

The core routine is the weekly water change. Tanks accumulate nitrate (the end product of the nitrogen cycle), dissolved organic compounds from fish waste and uneaten food, and trace minerals depleted by plants and uptake. The only reliable way to remove them is to remove water and replace it with fresh dechlorinated water. The amount and frequency depend on bioload: a heavily stocked tank may need 30–50% weekly; a lightly stocked planted tank may need 20% every two weeks. The water change guide covers the how, the how much, and the how often — and the one mistake (not treating the new water with dechlorinator) that destroys a tank overnight.

The second routine is gravel vacuuming. Detritus settles into the substrate and decomposes; in an unplanted tank this is pure pollution. A gravel vacuum siphons water while churning the substrate to lift detritus out without removing the substrate itself. In planted tanks with soil substrates the rules are different — you vacuum the surface only, never churn the soil, because the soil is doing the filtration. The gravel vacuum guide covers both use cases plus the siphon-start trick that does not involve a mouthful of tank water.

The third routine is filter maintenance — and it is the routine most often done wrong. The instinct is to clean the filter thoroughly: rinse the media, scrub the impeller, replace the cartridge. Each of these nukes the bacterial colony that does your filtration. Filter media should be rinsed in old tank water (never tap water — chlorine kills bacteria), the cartridge should be squeezed rather than replaced unless it is physically disintegrating, and only half the media should be cleaned at any one time. The filter tips guide covers what to clean, when, and how — and how to recognise the symptoms of a filter that has been over-cleaned.

Cycling is not a setup task — it is an ongoing maintenance concern. Every time you over-clean the filter, every time you medicate the tank, every time the power goes out and the filter stops for six hours, your bacterial colony takes a hit. A mature tank recovers within days; a young tank may crash. The cycling guide covers fishless cycling for new tanks and the recovery protocols for established tanks that have taken a bacterial hit. Read it before you need it.

Nano tanks (under 10 gallons) are a maintenance category of their own. Small volumes swing faster — a missed water change in a 5-gallon tank can spike ammonia to lethal levels; in a 55-gallon tank the same missed change barely registers on a test. The nano tank maintenance guide covers the abbreviated schedules that work for small tanks, the equipment that makes maintenance easier (python water changers, battery backup, automatic feeders), and the warning signs that a nano tank is about to crash.

Setup is the foundation maintenance is built on, and a poorly set up tank is a high-maintenance tank forever. The setup walkthrough covers the order of operations on day one — substrate, hardscape, water, cycling, planting, fish — that determines whether you spend the next year maintaining a tank that mostly takes care of itself or fighting a tank that never quite stabilises.

The minimum viable maintenance schedule

For most community tanks the floor is: a 20–30% water change every week, gravel vacuum of the visible substrate every two weeks, filter media rinse in tank water once a month, glass scrape as needed, and a parameter test (ammonia, nitrite, nitrate) every two weeks. Heavily stocked tanks add a second water change per week. Planted Walstad tanks can drop to a 20% change every two weeks. The schedule is not religious — your test kit tells you whether you are doing enough. If nitrate stays below 20 ppm between changes, you are fine. If it climbs above 40 ppm, you are behind. If ammonia or nitrite is ever detectable, something has gone wrong and you need to fix it that day, not next weekend.

Pair the water change guide with the Tank Size Calculator — knowing your true water volume (after substrate and decorations) tells you exactly how many litres to remove for a given percentage change. Guessing volume is how people accidentally change 60% of a tank they thought held more water than it does, and shock their fish.

One last point: maintenance is not optional and it is not seasonal. The aquarists who quit the hobby almost always cite the maintenance load — but they are usually maintaining tanks that were badly set up, badly stocked, or badly filtered in the first place. A well-set-up tank takes ten minutes a week. A badly-set-up tank takes an hour and a half. The setup and stocking guides in the other categories exist partly to reduce the maintenance load — the routines here are the floor, not the ceiling.