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How to deep clean your fish tank - 8 easy steps

As anyone that keeps any kind of animal will know, their care and maintenance takes work and as with any other pet, keeping fish (whether tropical or cold water) can be a challenge. You need to think about fish compatibility, water temperature, PH, tank volume, oxygen levels, filtration, food and the list really does go on. 

A critical part of keeping your fish healthy is to keep your tank clean. In our recent blog post, we suggested some of the best algae eating fish, snails and more that you can introduce into your eco system to help naturally keep your tank free of algae or with healthy levels of algae. However, keeping algae eating fish is not a substitute for manually keeping your tank and its components clean. Ultimately, keeping your aquarium and its components clean will maintain a happy and healthy environment that your fish and other critters can thrive in. 

In this blog post, we’ll give you a step-by-step guide to properly cleaning your aquarium that you can easily follow. This will also include our best advice when it comes to replacing parts as and when needed. 

Before we get started though, we’ll answer the most common question that we get asked: ‘how often should I clean my fish tank?’. 

Well, unfortunately, the answer to this question is that it depends on a number of factors. These include how effective your pumps and filters are, water treatments and quality, what fish you have in your tank, how many of them, the size of your tank and more. Having said that, nothing frustrates us more than a vague answer so if you’re looking for a general rule or routine you can get yourself into, then we suggest cleaning your tank at least every two weeks. 

Some great tools you can use to make the process easy include:

Step 1: Clean the inside of the glass

cleaning the glass of a fish tank

If you’re new to cleaning tanks then you may be surprised that the first step isn’t to empty your tank or to remove your fish. In fact, it’s perfectly safe to clean your tank with your fish in there so long as you move slowly and carefully. We recommend replacing 25-40% of your tank’s water every week, so there should still be plenty of water for your fish to swim around in while you clean. It’s also important to know that replacing 10% of your tank’s water four times isn’t as good as replacing 40% of your tank’s water in one go. 

We advise that step one of cleaning your aquarium tank is to clean the inside of the glass - front, back and sides. This is made easier by using some of the tools suggested above - such as a glass scraper, cleaning cloth or algae cleaning mitt. 

We recommend that you wear long waterproof gloves when cleaning your tank to keep your hands warm and dry. If you come across a stubborn patch of grime or algae, then we recommend using a scraper or magnetic scraper. We have recommended some suitable tools above. 

At this point we’ll highlight just how important it is to buy specialist tools rather than to use supermarket bought cleaning products or cloths. Firstly, professional aquarium scrapers are designed to not scratch your tank. Secondly, store-bought cloths, or cloths from around your home may contain cleaning residue which could harm or even kill your fish. Ultimately, it’s better to be safe than sorry - so invest in suitable cleaning tools for the best results. 

Step 2: Clean your tank decorations and large rocks

cleaning rocks and decorations in your fish tank

Your coral ornaments, plastic plants, large rocks and other cool decorations from diver helmets to volcanoes all need cleaning every couple of weeks to keep them in good condition. Of course, a little algae growth can look nice and enhance the look of your aquarium, but you really want to keep on top of your cleaning regime to ensure that algae and grime doesn’t take over! 

The best way to clean your fish tank decorations is to remove them from the tank and submerge them in a bucket of warm water. Use this warm water and give your decorations a good scrub with an algae scraper. This should do the trick. 

If your decorations are still not cleaning up as well as you would like, then resist the temptation to use soap. Soaps can be really harmful to your fish and no matter how well you feel you have rinsed your decorations, it’s likely some soap residue will remain. Instead, prepare a 10% bleach, 90% water solution. Then soak your decorations in it for 10-15 minutes. This should do the trick. 

Don’t put your decorations back for now - you need to complete the next few steps first.

Step 3: Trim your plants

trimming aquarium plants

You may have some live plants in your tank, in which case now is the perfect time to give them a trim. Simply take a pair of clean scissors and prune your plants (preferably with one pair of scissors that are used only for your tank plants). 

If you have floating plants that are covering the surface of your aquarium then remove about half of them so that you can be sure that your fish are getting enough light and oxygen. As nice as it is to see plants thriving, you don’t want them to take over your tank and starve your fish of light and oxygen. 

Step 4: Clean your stones, gravel or sand

cleaning stones and gravel in a fish tank

Now that your tank glass is clean, empty of decorations and your plants have been pruned, you should have plenty of room in there to get access to your gravel. 

Using a gravel vacuum, you can easily clean rock, gravel or sand in your tank. This will remove loose debris from the bottom of your tank. We recommend vacuuming 25-50% of your gravel weekly, but this step should certainly be part of your deeper cleaning routine. This is also more effective when done while your decorations are out of the tank, as debris can gather under the decorations.

Step 5: Change a portion of your water

siphoning water from a fish tank

We recommend changing 25-40% of your water each week. Siphon the water you are removing into a bucket. Then, replace the water you removed with fresh, treated water that is at the same temperature as the rest of the water in your aquarium. 

Step 6: Check / clean your filter

checking and cleaning your filter

Ideally, your filter should be cleaned once per month. We would recommend, if you can, to alternate your cleaning routine between your tank and your filter. This is because when you give your tank a thorough cleaning you will disturb beneficial bacterial colonies and you need these colonies to eliminate the toxins. Your filter will contain these beneficial bacterial colonies, so leaving your filter as it is for a week or two after your clean can help to keep your ecosystem stable and avoid triggering an ammonia spike. 

Step 7: Restore your tank decorations and fish

putting tank decorations back after cleaning

If you decided to change a large percentage of water then you may have chosen to temporarily displace some fish. If that’s the case, then now is the time to return them safely to your aquarium along with your decorations. 

Step 8: Clean the outside of your aquarium

cleaning the outside of an aquarium

Now that the inside of your aquarium is looking nice and clean, give the outside of your tank a wipe and clean any dust off your aquarium lid, stand and lights. Now you can sit back and enjoy looking at your pristine tank..