Reference
What to Do, and How Often
Almost every problem on this site is a maintenance interval that slipped. The table below is a starting point rather than a law — a heavily stocked twenty-gallon tank and a lightly stocked planted seventy-five will not run on the same rhythm. What matters more than the exact numbers is that the intervals are fixed and written down, because a tank that is looked after on a schedule almost never presents you with a surprise.
19 tasks across 5 intervals
Before your hands go in
Anything electrical comes out of the socket before your hands go in the water. Heaters, filters, powerheads and lights — unplug at the outlet, and leave a heater unplugged until the glass is fully submerged again.
Everything, in one table
The last column is the one worth reading. Very few of these intervals are fixed — they move with how heavily the tank is stocked, how much goes in at feeding time, and whether there are plants doing some of the work for you.
| Task | Interval | Time | Why | What shifts it |
|---|---|---|---|---|
| Look at the tank properly | Daily | 1 min | Counting the fish and watching how they behave for thirty seconds catches almost everything early — a missing animal, a filter that has stopped, a heater stuck on. | Nothing shortens this. New tanks and newly added fish deserve two looks a day rather than one. |
| Feed, and watch the food go | Daily | 2 min | Feeding is the largest input you control. Watching it lands the portion correctly: anything still on the substrate after a minute or two was too much. | Fry and some small species need more frequent feeding; most adult community fish do well with one skipped day a week. |
| Check the water temperature | Daily | 1 min | A heater fails in one of two directions and both are quiet. A glance at an in-tank thermometer costs nothing and catches it the same day. | Tanks near a window, near a vent, or in a room that cools sharply at night want a morning and an evening reading rather than one. |
| Test ammonia and nitrite | Daily | 10 min | During a cycle these two numbers are the whole picture, and the daily trend is what tells you whether to wait or to change water. | This is a cycling-only task. Once a tank has held zero on both for several weeks, it drops back to the weekly test. |
| Change 20 – 30% of the water | Weekly | 25 min | The one action that removes nitrate and dissolved organics rather than converting them. Everything else on this list is easier when this one is kept. | Heavier stocking, more feeding, or a tap supply that already carries nitrate all push toward more frequent changes. Substantial live plant mass and light stocking push the other way. |
| Vacuum a section of the substrate | Weekly | included above | Most of a tank's stored waste is in the top layer of the bed. Taking a third of it at a time keeps the whole bed serviced without disturbing everything at once. | Sand beds and heavily planted tanks want a lighter touch on the surface only. Bare-bottom tanks need a siphon of the floor instead. |
| Test the four core parameters | Weekly | 15 min | A weekly record of ammonia, nitrite, nitrate and pH turns a set of numbers into a trend, and trends are what give you warning. | Test daily during a cycle, and after any change to stocking, filtration or maintenance routine. |
| Clear the filter intake and squeeze the mechanical media | Weekly | 5 min | A blocked intake is the most common cause of lost flow, and saturated floss stops filtering long before it looks full. | Tanks with fine-leaved plants or heavy feeding need the intake cleared more often; a covered intake in a bare tank can go two weeks. |
| Wipe the glass and remove visible algae | Weekly | 5 min | Soft growth comes off with a cloth in seconds. Left for a month it hardens and needs a blade. | Tanks in bright rooms or on long photoperiods need this twice a week; shaded tanks on a six-hour timer can stretch it. |
| Test KH alongside pH | Every two weeks | 5 min | KH is the early warning for every pH problem. A buffer that is trending down gives weeks of notice before the pH moves visibly. | Soft tap water, driftwood, peat or botanicals all consume buffer faster and justify a weekly check. |
| Trim dying leaves and thin fast-growing plants | Every two weeks | 10 min | A leaf that dies in the tank becomes nitrate in the tank. Removing plant mass is one of the few genuine nutrient exports available to you. | Fast stem plants under strong light may want this weekly. Slow-growing anubias and ferns need it only occasionally. |
| Top up evaporation with treated water | Every two weeks | 5 min | Evaporation removes water and leaves everything dissolved in it behind, so topping up with treated fresh water keeps the concentration where it was. | Dry rooms, open tops and strong surface agitation all raise the rate — this is where knowing your room humidity is genuinely useful. |
| Replace one piece of chemical media | Monthly | 10 min | Activated carbon and organic resins are consumables with a working life of roughly a month. Past that they occupy space without doing anything. | Heavily stocked tanks exhaust chemical media faster. Follow the interval printed on the packaging for the product you actually use. |
| Rinse biological media in used tank water | Monthly | 10 min | Sponges and biomedia clog with fine debris and lose flow. A gentle rinse in removed tank water clears them without touching the colony. | Do this more often in a heavily fed tank. Never do it under a running tap, and never replace every piece in the same session. |
| Check equipment and cables | Monthly | 5 min | Heater suction cups fail, cables chafe, and a drip loop that was there at setup can get dressed away later. This is a safety item first. | Any tank that has been moved, rewired, or added to gets this check immediately rather than at the next interval. |
| Deep clean the filter housing and impeller | Quarterly | 30 min | Fine sludge collects under the media basket and in the pump chamber, and the impeller picks up hair and plant fiber that eventually costs flow and adds noise. | Do it sooner if flow drops or the unit becomes noisy. Unplug the filter at the outlet before opening it. |
| Verify the thermometer against a second one | Quarterly | 5 min | Inexpensive thermometers drift, and a heater set correctly against a wrong reading is a heater set wrongly. | Check immediately if fish behavior and the thermometer disagree, or after the thermometer has been in direct sun. |
| Test the tap water | Quarterly | 15 min | Municipal supplies change. Nitrate, KH, pH and the choice of disinfectant can all shift, and each of those changes what a water change does to your tank. | Test immediately after any notice from your utility, after a move, or if water changes stop producing the effect they used to. |
| Review stocking and feeding honestly | Quarterly | 10 min | Fish grow. A stocking level that was comfortable in spring can be the reason nitrate will not come down by autumn. | Do this whenever fish are added, or whenever nitrate returns to a high reading within days of a large water change. |
By interval
Daily
Two minutes, and it catches almost everything early.
Look at the tank properly
Counting the fish and watching how they behave for thirty seconds catches almost everything early — a missing animal, a filter that has stopped, a heater stuck on.
Shifts with: Nothing shortens this. New tanks and newly added fish deserve two looks a day rather than one.
Feed, and watch the food go
Feeding is the largest input you control. Watching it lands the portion correctly: anything still on the substrate after a minute or two was too much.
Shifts with: Fry and some small species need more frequent feeding; most adult community fish do well with one skipped day a week.
Check the water temperature
A heater fails in one of two directions and both are quiet. A glance at an in-tank thermometer costs nothing and catches it the same day.
Shifts with: Tanks near a window, near a vent, or in a room that cools sharply at night want a morning and an evening reading rather than one.
Test ammonia and nitrite
During a cycle these two numbers are the whole picture, and the daily trend is what tells you whether to wait or to change water.
Shifts with: This is a cycling-only task. Once a tank has held zero on both for several weeks, it drops back to the weekly test.
Weekly
The block of work that keeps a tank out of trouble.
Change 20 – 30% of the water
The one action that removes nitrate and dissolved organics rather than converting them. Everything else on this list is easier when this one is kept.
Shifts with: Heavier stocking, more feeding, or a tap supply that already carries nitrate all push toward more frequent changes. Substantial live plant mass and light stocking push the other way.
Vacuum a section of the substrate
Most of a tank's stored waste is in the top layer of the bed. Taking a third of it at a time keeps the whole bed serviced without disturbing everything at once.
Shifts with: Sand beds and heavily planted tanks want a lighter touch on the surface only. Bare-bottom tanks need a siphon of the floor instead.
Test the four core parameters
A weekly record of ammonia, nitrite, nitrate and pH turns a set of numbers into a trend, and trends are what give you warning.
Shifts with: Test daily during a cycle, and after any change to stocking, filtration or maintenance routine.
Clear the filter intake and squeeze the mechanical media
A blocked intake is the most common cause of lost flow, and saturated floss stops filtering long before it looks full.
Shifts with: Tanks with fine-leaved plants or heavy feeding need the intake cleared more often; a covered intake in a bare tank can go two weeks.
Wipe the glass and remove visible algae
Soft growth comes off with a cloth in seconds. Left for a month it hardens and needs a blade.
Shifts with: Tanks in bright rooms or on long photoperiods need this twice a week; shaded tanks on a six-hour timer can stretch it.
Every two weeks
The slower half of maintenance, easy to let slip.
Test KH alongside pH
KH is the early warning for every pH problem. A buffer that is trending down gives weeks of notice before the pH moves visibly.
Shifts with: Soft tap water, driftwood, peat or botanicals all consume buffer faster and justify a weekly check.
Trim dying leaves and thin fast-growing plants
A leaf that dies in the tank becomes nitrate in the tank. Removing plant mass is one of the few genuine nutrient exports available to you.
Shifts with: Fast stem plants under strong light may want this weekly. Slow-growing anubias and ferns need it only occasionally.
Top up evaporation with treated water
Evaporation removes water and leaves everything dissolved in it behind, so topping up with treated fresh water keeps the concentration where it was.
Shifts with: Dry rooms, open tops and strong surface agitation all raise the rate — this is where knowing your room humidity is genuinely useful.
Monthly
Consumables and safety checks.
Replace one piece of chemical media
Activated carbon and organic resins are consumables with a working life of roughly a month. Past that they occupy space without doing anything.
Shifts with: Heavily stocked tanks exhaust chemical media faster. Follow the interval printed on the packaging for the product you actually use.
Rinse biological media in used tank water
Sponges and biomedia clog with fine debris and lose flow. A gentle rinse in removed tank water clears them without touching the colony.
Shifts with: Do this more often in a heavily fed tank. Never do it under a running tap, and never replace every piece in the same session.
Check equipment and cables
Heater suction cups fail, cables chafe, and a drip loop that was there at setup can get dressed away later. This is a safety item first.
Shifts with: Any tank that has been moved, rewired, or added to gets this check immediately rather than at the next interval.
Quarterly
The deep work, plus the assumptions worth re-testing.
Deep clean the filter housing and impeller
Fine sludge collects under the media basket and in the pump chamber, and the impeller picks up hair and plant fiber that eventually costs flow and adds noise.
Shifts with: Do it sooner if flow drops or the unit becomes noisy. Unplug the filter at the outlet before opening it.
Verify the thermometer against a second one
Inexpensive thermometers drift, and a heater set correctly against a wrong reading is a heater set wrongly.
Shifts with: Check immediately if fish behavior and the thermometer disagree, or after the thermometer has been in direct sun.
Test the tap water
Municipal supplies change. Nitrate, KH, pH and the choice of disinfectant can all shift, and each of those changes what a water change does to your tank.
Shifts with: Test immediately after any notice from your utility, after a move, or if water changes stop producing the effect they used to.
Review stocking and feeding honestly
Fish grow. A stocking level that was comfortable in spring can be the reason nitrate will not come down by autumn.
Shifts with: Do this whenever fish are added, or whenever nitrate returns to a high reading within days of a large water change.
What a slipped interval actually looks like
Nothing on this list is urgent on the day it is missed. The cost shows up weeks later, as a problem that does not obviously connect back to the thing you skipped. These are the usual pairings.
- Water changes stretched from weekly to fortnightly, then monthly: nitrate climbs, algae stops being occasional, and the tank starts to look tired. See Nitrate is high no matter how often I change water.
- The substrate never vacuumed in the same place twice: material accumulates out of reach, and one day the tank smells with clean test results. See All four readings are fine but the tank smells bad.
- KH not tested for months: the buffer runs out quietly and the pH moves suddenly. See My pH reads differently every time I test it.
- The intake strainer never cleared: flow falls, dead spots appear, and growth settles where the water stopped moving. See The filter output has slowed to a trickle.