Guides
Practical guides
The first article in this section is about the most frequent task in a fishkeeper's life: the water change. By regularly replacing part of the water, you remove accumulated nitrate and keep conditions stable. Below is a calm sequence of steps that suits most home freshwater aquariums.
A good water change goes unnoticed by the fish. If they dart about or hide afterwards, the new water was more different from the old than it should have been.
What to have ready
- A separate bucket or container used only for the aquarium and never washed with household cleaners.
- A gravel vacuum with a hose for draining water and cleaning the substrate.
- Water that has been left to stand, or a water conditioner if your tap water is treated with chloramine.
- A thermometer to compare the temperature of the new water with the tank water.
- A soft sponge or scraper for the glass, and an old towel for the floor.
- An aquarium diary or notes on your phone.
Prepare the water in advance
Fill a clean container with tap water. Chlorine will leave if the water stands, but chloramine isn't removed that way, so if it's present, use a dedicated water conditioner following the manufacturer's instructions.
Hypothetical example: a fishkeeper learns from the local water supplier that chloramine is used in the city's water and starts adding conditioner instead of just letting the water stand.
Match the temperature
Use a thermometer to compare the new water with the tank water. A sudden jump in warmth or cold stresses fish, so the new water should be close in temperature.
Hypothetical example: the water in the bucket is noticeably cooler than the tank water, so it is left to stand in the room until the difference disappears.
Switch off the equipment
Turn off the heater and, if draining will lower the water level a lot, the filter too. A heater left above the surface can overheat, and a filter without water can run dry.
Hypothetical example: an owner sticks a reminder note next to the socket so as not to forget to switch the equipment back on after the water change.
Drain part of the water with a gravel vacuum
Push the vacuum into the substrate and move it slowly across the bottom, picking up leftover food and waste. Drain only part of the water, not all of it: a full change upsets the established balance.
Hypothetical example: a beginner notices that more debris collects under an ornament than on the open bottom, and now gives that spot attention every time.
Tidy up inside
While the water level is low, wipe the film off the glass and remove dead plant leaves. Ornaments don't need scrubbing until they shine: beneficial bacteria live on them too.
Hypothetical example: an aquarium owner stops scrubbing the stones with a brush every week and notices the water turns cloudy less often after changes.
Rinse the filter sponge the right way
If the filter is clogged, rinse the sponge in the tank water you have just drained, not under the tap. Chlorinated water and hot rinsing kill the bacterial colonies that process ammonia.
Hypothetical example: a fishkeeper cleans the filter and changes the water on different days so the bacteria don't have to cope with two changes at once.
Top up with new water slowly
Pour the prepared water in a thin stream, aiming it at your palm, a stone or the glass so it doesn't disturb the substrate or frighten the fish.
Hypothetical example: a clean plate is placed on the bottom of the tank and the water is poured onto it so the stream doesn't stir up debris.
Switch the equipment on and note the result
Turn on the filter and heater, check that everything is working and watch the fish for a while. Write the date in your diary along with anything that seemed unusual.
Hypothetical example: from the diary, an owner sees that the fish are sluggish every time a water change is skipped, and stops putting it off.
Common mistakes
- Changing all the water at once: it robs the aquarium of stability and disrupts the bacteria.
- Pouring water straight from the tap without removing chlorine or treating chloramine.
- Washing the filter sponge in hot tap water or with detergent.
- Using a bucket for the aquarium that was previously used to wash floors with cleaning products.
- Forgetting to switch the heater and filter back on after the water change.
- Putting off water changes for weeks, then trying to catch up with one big clean-up.
If something doesn't fit
- If you don't have a gravel vacuum, a clean hose will do at first, but clean the substrate more carefully.
- If carrying buckets is hard, do smaller water changes more often: it's even calmer for the fish.
- If you're not sure whether your water contains chloramine, ask your water supplier or use a conditioner designed for both substances.
Check yourself
- The new water is free of chlorine or treated with conditioner
- The new water is close to the tank water in temperature
- The heater was switched off before draining
- Only part of the water was drained; the substrate was vacuumed
- The filter sponge was rinsed in tank water
- The water was topped up slowly, without clouding
- The filter and heater are running again
- The date of the water change is in the diary
Catalogue of English articles
This is where we will collect standalone articles for beginner fishkeepers written for English-speaking readers: practical walkthroughs, answers to common questions and explanations of the basics.
- Aion 2 arcana guide: Practical Overview for Players
How to approach Arcana in Aion 2: where to find reliable details, a step-by-step method for learning any new progression system, and pitfalls to avoid.
- GTA 6 Player Assistance and Boosting Options: What Players Should Know
A comparison of GTA 6 player assistance types, from coaching to account sharing, with confirmed facts, labelled speculation and terms-of-service risks.
- Fortnite: V-Bucks — Player Experience Analysis
What V-Bucks are in Fortnite, how players get them through official routes, common scams, Epic's rules on third-party sellers and practical alternatives.
- Understanding Call of Duty lobby matchmaking: Learning Resources
A plain-language look at Call of Duty lobby matchmaking, skill-based matchmaking debates, bot lobby services, account risks and where to keep learning.
What we're working on
- How to get through the first weeks of cycling a tank calmly, without giving in to the urge to add fish straight away.
- How to prepare your aquarium for a holiday, and why an automatic feeder isn't always the best answer.
- How to bring new fish home through quarantine without passing disease to the rest of the tank.
- How to pick easy live plants for a first aquarium and care for them without complicated equipment.
- How to rehome fish responsibly when you move house or can no longer keep the aquarium.
How we publish
- Articles in this catalogue are written separately for each language version and are not translations.
- Some articles link to third-party websites, including gaming services; we do not control their content, prices or terms.
- We do not sell animals or equipment and do not publish advertising for shops or brands, rankings, prices or reviews.
Read next
- Questions
Short answers about tap water, which fish get along, everyday care and the first signs of trouble.
- Reference
A fishkeeper's glossary: nitrogen cycle, nitrite, water conditioner, quarantine, schooling fish and more.
- Sections
Four big topics: water and the nitrogen cycle, equipment, aquarium inhabitants and regular care.
Sources
- Beginner fishkeeping handbooks
- General guidance on preparing tap water for aquariums
Information is current as of the date this page was prepared. Fish, plants and invertebrates vary widely in their needs, so before buying a new animal, always check the requirements of that particular species.