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How to Clean a Fish Tank

So you’ve set up your aquarium, cycled it and have got everything up and running. Fish are happy, plants are growing… time to lean back and relax, right? Sure, but don’t forget that even a healthy fish tank needs regular cleaning.

Not sure what kind of maintenance your tank needs and when? We’ll explain all you need to know about how to clean a fish tank below.

Water change & substrate cleaning

The most important and frequent task to perform is water changing. Your aquarium should have a filter to make sure the water doesn’t become toxic in mere hours, but unfortunately even the best filter doesn’t eliminate the regular need for clean water. Some harmful substances, like nitrates, should be removed manually.

So how much water should you change and how often? Most aquarists choose to do weekly water changes. The exact amount varies greatly based on the stocking level and amount of plants in your aquarium. If you’re not sure what to start with, keep in mind that your nitrate levels should ideally be < 10. In most tanks that comes down to 20-30% a week, though your (liquid) aquarium test kit will help narrow it down.

The easiest way to remove water from your aquarium is by using a special water change hose. These make it easy to start the flow, with the end simply going down the drain or into your garden. Don’t forget to temperature match the new water and add it slowly after treating it with a dechlorinator.

Water change time is the perfect opportunity to clean the aquarium substrate. Because you’ll usually remove the old water with a hose, you can use this moment to ‘vacuum’ and remove debris like fish waste or dead plant bits.

Just make sure you don’t suck up any unsuspecting aquatic life: fish can be overly curious and end up going down the hose if you’re not careful. Some mosquito netting tied over the intake using a rubber band can be enough to avoid unpleasant incidents.

Cleaning aquarium glass

Cleaning the glass is not an essential part of aquarium maintenance, as your fish honestly won’t care if there’s some algae on there. However, since your aquarium is meant to be decorative, you’ll usually want to keep at least the front panel clean.

Gently clean the glass using a magnetic cleaner, scraper or even an old piece of aquarium sponge, making sure no sand gets under the cleaner to avoid scratches. We like to scrub the glass right before a water change, so that the debris that is released can then be vacuumed away immediately.

Cleaning aquarium filter

Although your filter doesn’t need weekly cleaning, it’s still very important not to forget about it. Dirty filters can become clogged, reducing the outflow and increasing the risk of a cycle crash. To make sure the beneficial bacteria population that inhabits the filter media stays happy and healthy, take the filter apart about once a month.

Replace filter floss if you’re using it and clean the sponges by squeezing them in a bucket of old tank water until dirt stops coming out. Biological filter media like ceramic rings should be left alone entirely apart from maybe a light swish to remove excess debris.

If the filter still appears clogged even after a good cleaning, it might be time to replace the sponges. Do NOT replace all the media at the same time: you’ll crash your aquarium’s cycle which can be fatal to your fish. Instead, try replacing about ⅓ with every filter cleaning, keeping a close eye on your water values to make sure everything is still in order.

Need help?

As we’ve discussed above, keeping your aquarium healthy involves several recurring tasks and can be quite time-consuming. Luckily, FantaSEA doesn’t just design and set up fish tanks: we also offer maintenance service. If you want to enjoy your aquarium with none of the hassle, see what we can do for you!

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Marijke Puts

Hey! I'm Marijke, FantaSEA's resident blog writer. I'm a full-time pop science author, part-time PADI diver and snorkeler, and have been keeping fish since I was a kid. When I'm not writing fish care guides, you can usually find me underwater or trying to figure out how to fit more tanks into my house.

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