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. Follow along as we share our top tips for cleaning your fish tank like a pro.

Before you start…

We often get asked a lot of questions from beginners. Let’s start with the most frequently answered:

How often do you need to clean a fish tank?

Some people say it once a week while others say it once a month. It really 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.

Do you take the fish out of the tank when cleaning?

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. The process of catching them can be more stressful than the slow cleaning.

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 school piece of advice comes from the fact that municipalities often put chlorine in tap water (which is lethal to fish), but if you let the water sit out for 24 hours, the chlorine evaporates. 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

We’ve clarified some of the confusion surrounding tank maintenance. Here is a step by step guide that you can follow on a daily basis.

Step 1: Test 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.) These waste compounds can pose a danger to fish if they reach high levels.

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: Get rid of Algae

An algae scraper is a great way to keep fish in view. If you have the blade attachment, it should be very easy to slice through any tough algae spots. Be careful not to catch substrate under the algae scraper or you could scratch the acrylic or glass.

It is possible to rinse off algae from the lid by running water into the sink. (Don’t use soap or it may harm 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. More tips can be found in our article How to Get Rid of Algae.

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. If you have tall stem plants, you can easily propagate them by cutting a few inches off the tops and replanting them into the substrate. If your vallisneria or dwarf sagittaria are spreading into unwanted areas, pull out the little runners and move them elsewhere. Finally, if the floating plants cover the entire surface of the water, you can remove 30% to 50% to ensure that the fish and plants below have enough light.

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 the equipment

Make sure you turn off all electrical equipment before you remove any water. 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 has two purposes. It removes fish waste, uneaten foods, and leaves from the gravel and sand. It also removes old tank water and excess nitrates. You can find detailed instructions for how to start a gravel vacuum and how to stop it if you have accidentally taken in a small fish.

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

Step 6: Clean the 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. Filters are actually more like trash cans. However, at the end, it is still your responsibility to empty the trash can. Filters also collect fish waste. However, you need to regularly clean them so that any gunk is removed before it gets clogged 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, do not use soap, just water.) If you have a spongefilter, remove the foam and run it through a bucket of old tank water. For more details, read the last section of our sponge filter article.

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). This is also your chance to add liquid fertilizer and/or root tabs for 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 Equipment

Although you just spent all this time cleaning the tank, it probably looks dirtier than ever with all that particulate clouding up the water. Don’t worry, just turn on the heater again and the filter will work overtime to remove the particulate.

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.