How to Clean a Fish Tank in 10 Steps (Aquarium Maintenance Tips)

Clean a fish tank should take place on a weekly basis to keep it clean and the fish healthy. Without regular aquarium maintenance, a fish tank will slowly become a mess both visibly and invisibly.

To understand why a fish tank needs regular maintenance, we must first know what is happening in a fish tank.

Fish eat fish food, and they produce fish poop. As a result, there will be toxic ammonia created as all the organic waste is breaking down. Thanks to the aquarium nitrogen cycle, the toxic ammonia will end up in the form of harmless nitrate.

While nitrate is non-toxic, it can still affect the fish’s immune system in high concentration. If we do not clean a fish tank for a long time, the nitrate concentration will be at an unhealthy level. Fish will be vulnerable to diseases when their immune system gets weaker. It is what people refer to as the Old Tank Syndrome. As a general rule of thumb, it is the best to keep nitrate concentration under 40ppm. The lower, the better.

As a result of more and more fish poop pile up at the bottom, the rotting organic matter will build up. Sometimes when there is too much fish poop, not even the established aquarium nitrogen cycle can keep the ammonia at bay. As a result, you might get an ammonia and nitrite spike in your aquarium. Both can kill the fish since they are toxic.

Furthermore, nitrate is a nitrogen compound. It is a food source for algae. Algae will start to grow everywhere if nitrate is not in check. You might even see the water turn green.
The production of nitrate is also acidic. It will slowly eat away at the water buffer. As a result, the water PH might crash (sudden large drop). Fish do not sudden large change in anything. It can shock and even kill them.

To prevent the mess from happening, we strongly recommend doing regular aquarium maintenance once a week. It is mainly to reduce the nitrate and other organic waste. It also for removing fish poop, cleaning the mineral deposit, and stop algae from building up. As well as to restore the water buffer to prevent the water become too acidic.

Now we know why we need to fish tank maintenance regularly. The next step is how to do it. As a part of maintenance, we need to do a 30~50% partial water change once a week as the main task. Any higher percentage might shock the fish; any lower amount might not be sufficient.

Everything about how to clean a fish tank can be narrowed down to the following ten steps

1. Prepare for Aquarium maintenance

To clean a fish tank, we must prepare everything forehand.

As a minimum, we need at least two buckets. A gravel vacuum. An algae scraper. A water conditioner.

Since there will be a water change, we need to prepare the clean water. Just use the tap water. And the fresh water should be in one of the buckets.

Make sure the new water temperature is very close to the old water in the fish tank. Or the fish might get in shock after the water change due to the sudden temperature drop. By very close, I mean no more than 3~5F in temperature difference. The less, the better.

Just let the new water sit in the bucket under room temperature for at least 24 hours. If the room temperature is too cold, use an aquarium heater to heat it up. Do not boil the water as it will deplete the oxygen in it.

The new water also must have aquarium water conditioner in it to neutralize chlorine and chloramine before use.

2. Turn everything electrical off

There are several pieces of electrical equipment in a fish aquarium. At the very least, there are the aquarium filter and the aquarium heater. When dealing with electrical stuff in the water, there is always the possibility of electricity leak. Better be safe. We should unplug them all before proceeding. The air pump can also be off. It will only serve as a distraction during the maintenance.

3. Clean the sides of the fish tank with an algae scraper

An algae scraper is easy to use. It can peel off all the buildups on the glass, including algae, mineral deposits, and organic buildup.

Do it slowly, and gently. Too large movements too quickly might scare the fish and put them under stress. There could be water spill as well if you are not careful.

4. Remove 30~50% water from the fish tank.

You may remove 30~50% the water from the aquarium by using a gravel vacuum to pull the water into an empty bucket.
While you are at it, use the gravel vacuum to suck up as much debris as you can from the bottom of the fish tank. All the fish poop, leftover fish food (should not be any if you do not overfeed), and anything unwanted should go in the bucket along with the removed water.

5. Clean the equipment and decoration (optional)

If you see buildups on the aquarium filter, heater, thermometer, and decorations, you might want to clean them too. You can wash everything under the tap water except for the filter media.

Most of the good bacteria colonies are on the filter media. We must not damage the bacteria colonies to maintain the aquarium nitrogen cycle. Or we will get ammonia and nitrite spike.  Tap water contains disinfect agents like chlorine and chloramine. Both might kill some of the bacteria. To prevent it from happening, we can wash the filter media in the just removed old tank water in the bucket. Gently squeeze the filter media or just wash off the debris if you have solid filter media.

Important: The good bacteria in filter media are aquatic. They can only survive in the water. Make sure the filter media stay wet. Do not let it leave water for more than a few minutes.

Return everything to the fish tank. After clean all the equipment and decorations, you may put them back to where they were.

6. Add the prepared clean water to the fish tank

Slowly add the fresh water back into the fish tank. You can directly dump it from the water bucket. Do it slowly, not to make a mess of the substrate, or scare the fish.

You can also use the intake of a filter system if you have an external filter such as canister filter. The intake of a canister filter system can suck the water into the fish tank from the bucket. It makes the water change easier and less disturbing to the fish.

7. Clean the fish tank wall on the outside

After all the earlier steps, there might be a little water on the outside of the aquarium. Use a piece of cloth or paper towel to wipe it. While you are at it, might as well clean off any fingerprint or dust mark. If you do not wipe off the water right now, it might leave a watermark later.

8. Turn everything back on

After you are sure you won’t need your hands in the water again, you can plug in everything. The aquarium filter, the heater, and the air pump all should be back to work.

9. Observe the aquarium to double check everything

Now everything is complete. You must continue to observe for at least a few minutes to make sure everything is alright. First, check to see if all the electrical equipment is working properly. Then check out the water temperature to see if it is close enough to what you wanted. Finally, pay attention to the behavior of the fish to see if there is anything out of the ordinary. If there is a problem, you’d want to notice it sooner than later.

10. Dump the old tank water and wash the gravel vacuum and algae scraper

Now you can dump the old tank water from the bucket. Throw it down the toilet, or use it for watering the garden.  It has nitrate which makes an excellent fertilizer for the plants.

Wash the bucket. You may fill the other bucket again to prepare the new water for the next water change.

You might also want to wash all the cleaning tools as well. Including the gravel vacuum and the algae scraper.  Because it will be harder to clean once they are dry.

Make aquarium maintenance a routine

Finally, clean a fish tank does not take more than 15~20 minutes each time.  Therefore, doing it on a weekly basis is easy, and it should become a habit. You may do it twice or even more often each week to keep the water at higher quality if you wish. Any less frequently might cause the buildup of algae and organic waste. I prefer doing it once a week. Too often means more work.  By doing weekly aquarium maintenance, it keeps your fish tank clean, and your fish healthy.