How to Properly Clean Your Fish Tank


How to Properly Clean Your Fish Tank

When people find out you keep fish, they probably imagine a crusty, algae-coated tank where you can barely see anything swimming inside. But with just a few easy steps, you can keep your aquarium looking like a beautiful work of art. Keep reading to learn our top tips on cleaning fish tanks like a professional.


Before you start…

There are several frequently answered questions we often hear from beginners, so let’s address those first:

How often do you need to clean a fish tank?

Some people say it once a week while others say it once a month. The real answer is that it totally depends! It all depends on the size of your aquarium, how many fish are kept, and the amount of biological filtration (e.g. beneficial bacteria and live plant) that you have. Fortunately, we have a free guide to help you figure out exactly what frequency is right for your aquarium.

When cleaning out the tank, do you remove the fish?

No, go ahead and leave your fish in the aquarium. You won’t be completely draining the aquarium, so there will be plenty of water left for them to swim in. It is also more stressful to catch them than cleaning around them slowly.

There’s no need to catch the fish before cleaning an aquarium because it will only cause undue stress.

How long should water be left to cool before you add fish?

This old-fashioned advice stems from the fact municipal water systems often contain chlorine, which is fatal to fish. But if the water is left out for 24hrs, the chlorine will evaporate. Chloramine, a stable form of chlorine, is used in tap water. It does not evaporate over time. Instead, you need to dose water conditioner to make the water safe for fish, and then you can immediately use the dechlorinated water for your aquarium with no wait time.

What cleaning supplies are you looking for?

If this is your first aquarium, you may need to collect some tank maintenance materials, such as:

Aquarium water test kit – Bucket for holding dirty tank water – Algae scraper (for glass or acrylic) – Algae scraper blade attachment (for glass or acrylic) – Toothbrush for cleaning algae off decor or plants – Scissors for pruning plants – Dechlorinator (also known as water conditioner) Glass cleaner – Towel for wiping up water spills – Glass-cleaning cloth or paper towel – Aquarium siphon (also known as a gravel vacuum)

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How to Clean Your Aquarium

After clearing up any confusion regarding tank maintenance, here’s a step-by–step guide you can use on a regular basis.

Step 1: Assess the water quality

If your aquarium is newly established and has not been cycled yet, you need to test the water to determine if it has 0 ppm ammonia, 0 ppm nitrites, and less than 40 ppm nitrates. (For more info, find out how to cycle your aquarium.) Fish can become sick if they are exposed to higher levels of these compounds.

If your aquarium is already cycled, then the goal is to keep nitrate levels below 40 ppm. To determine the amount of water that should be removed from your aquarium and to determine if you need to take any other steps (based on our guide to water changes), use a water test kit.

A water test kit helps you determine if there are toxic levels of nitrogen waste compounds in the aquarium.

Step 2: Eliminate Algae

To keep your fish’s eyes open, use an algae scraper to clean the tank walls. If you have the attachment blade, it should be easy to cut through any hard algae spots. Be careful not to catch substrate under the algae scraper or you could scratch the acrylic or glass.

If algae has grown on the lid, you can easily rinse it off in the sink. You should not use soap as it can cause damage to your fish. Finally, if algae covers your aquarium decor, rocks, or plants, try using a clean toothbrush to gently brush it off, either over the sink or in the aquarium. For more information on how to remove algae, see our article.

Keep algae under control by regularly removing it and balancing the lighting and nutrient levels in your aquarium.

Step 3: Prune your plants

If you keep live aquarium plants, take this time to remove any dead leaves and trim down overgrown foliage. To propagate tall stem plants, cut a few inches off their tops and place them back into the substrate. If dwarf sagittaria and vallisneria are spreading into unwelcome areas, you can pull out the runners and move them to another area. If floating plants are covering the entire surface of your water, take out 30% to 50% and move them elsewhere. This will ensure that the plants below receive enough light and oxygen, as well as the fish.

Pruning helps plants to focus on delivering nutrients to the healthiest leaves, and it also allows light to reach leaves at the bottom of the stems.

Step 4: Turn off Equipment

Before removing any water, make sure to turn off or unplug all equipment. Aquarium heaters and filters are not meant to operate without water and therefore can become damaged when running in dry air.

Step 5: Vacuum the Substrate

Take out your nifty aquarium siphon and vacuum approximately one-third of the substrate. As debris can collect under decorations and hardscape, it is important to remove them as soon as possible. The siphon serves the dual purpose of not only removing fish waste, uneaten food, and dead leaves from the gravel or sand, but also removing old tank water and the excess nitrates in them. For detailed instructions on how to set up a siphon and how to stop it from sucking small fish, please see our gravel vacuum article.

Siphons can be used to quickly change water without the need for a pitcher or cup.

Step 6: Clean your filter

You should clean your filter at least once per month. Many beginners think of filters like a black hole where fish poop and detritus magically disappear from the water. In reality, filters are more like trash cans that collect waste, but at the end of the day, someone is still responsible for taking out the trash can. In the same way, filters collect fish waste, but you must still regularly clean it to remove all the gunk before the filter gets clogged up or overflows.

The easiest way to maintain a corner box, canister or hang-on-back filter is to simply wash it in a bucket of tank water. Again, don’t use soap. Just water. If you have a spongefilter, remove the foam and run it through a bucket of old tank water. You can read our last section on sponge filters for more information.

Step 7: Refill the Water

At this point, you can finally refill the tank with fresh, clean water that matches the temperature of the existing aquarium water. Human hands are able to detect temperatures within one or two degrees, so just adjust the faucet until the tap water feels like it has the same amount of warmth. You can empty the bucket of tank water, which can be used for indoor and outdoor plants, and then refill it with water. You can either add dechlorinator into the bucket (dosed based on the bucket’s volume) or directly into the tank (dosed based on the aquarium’s volume). You can also add liquid fertilizer or root tabs to the substrate.

If you’re worried about messing up your aquascape or substrate, pour the new water into the aquarium through a colander or onto another solid surface (like your hand or a plastic bag) to lessen any disturbances.

Step 8: Turn on the Equipment

Despite all the effort you put into cleaning the tank, the water is likely to look even worse because of all the particulate that has built up. Not to worry – turn on the heater and filter again, and within an hour or so, the debris will settle down or get sucked up by the filter.

Step 9: Clean the glass

For that extra, crystal-clear finish, wipe down the outside walls of the tank with aquarium-safe glass and acrylic cleaner to remove any water spots and smudges. Also, clean off the dust that has collected on the lid, light, and aquarium stand. Now you have a truly Instagram-worthy aquarium ready to wow your friends and family!

Get pleasure from the fruits and vegetables of your labor by spending hours gazing at your healthy, happy fish.