You should clean a fish tank a little every week, not a lot occasionally. A 25% water change and gravel vacuum weekly keeps water clear and fish healthy far better than an occasional deep clean.
Here is the schedule that works for a UK community tank.
- Do a 25% water change and gravel vacuum weekly — consistent small maintenance beats occasional deep cleans.
- Rinse filter media monthly in old tank water, never tap water.
- Never do a 100% water change or full deep clean; it crashes the beneficial bacteria.
- A healthy tank is not sterile — the goal is removing waste while preserving beneficial bacteria.
Weekly (20 minutes)
- 25% water change with dechlorinated water at matching temperature.
- Gravel vacuum to remove waste.
- Wipe the front and side glass.
- Test ammonia, nitrite and nitrate.
Full detail in how to clean a fish tank.
Monthly
- Rinse filter media in old tank water (never tap water).
- Trim plants.
- Clean the outside glass.
- Check heater and filter are working correctly.
Never do this
Never do a 100% water change or a full deep clean. A tank is not meant to be sterile — the beneficial bacteria that keep ammonia at zero live on the filter and substrate. Stripping everything clean crashes the cycle and stresses fish.
Frequently asked questions
How often should I do a water change on my fish tank?
Do a 25% water change weekly for a normally stocked community tank. Increase to twice weekly if nitrate stays above 40 ppm.
Should I clean my fish tank every week?
Yes — a light weekly clean (water change, gravel vacuum, glass wipe, water test) keeps conditions stable. This is far better for fish than an occasional heavy clean.
Can I clean my fish tank too much?
Yes. Over-cleaning — full water changes, scrubbing everything, or rinsing filter media in tap water — destroys the beneficial bacteria and forces the tank to re-cycle, harming fish.
— Jaqline Smalling, FishForever
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