How to Clean Your Fish Tank?

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Whether you have a freshwater aquarium or a saltwater aquarium, regularly cleaning your fish tank is a must if you want your fish to stay healthy.

Skipping regular tank maintenance is bad news for your fish. A tank that harbors harmful bacteria promotes further bacterial growth and favors the development of diseases.

A tank in which diseases thrive will no longer allow your fish to thrive. And I’m fairly certain you don’t want that to happen.

If you want to ensure that your fish are safe from diseases, do yourself and your fish a favor and do some regular cleaning.

If you’re a beginner and you feel overwhelmed by the task, don’t worry, in this article I’ll walk you through all the steps you must take to successfully clean your aquarium.

In this guide I discuss the cleaning process of both freshwater and saltwater aquariums, so you’ll know what to do regardless of your aquarium.

Why Clean Your Aquarium?

If you imagine that regularly cleaning your tank means getting out all the fish, removing everything from the tank and scrubbing the tank clean, you would be wrong.

First, removing the fish every time you’re doing maintenance will stress them out, not the mention you can even harm them physically, so keep the fish in the tank and don’t scare them with any vigorous movements.

Removing all the decorations from the tank is also not recommended.

All surfaces in the tank – including decorations! – grow beneficial bacteria and removing these can throw off the bacteria ecosystem.

What I mean by tank cleaning is none of the above, but instead the performance of regular 10 to 15% water changes, which has the following benefits:

Reduction of Harmful Compounds

Water changes help control the levels of ammonia, nitrite and nitrate in your aquarium. In the incipient stages of the Nitrogen Cycle, ammonia in your tank turns into nitrite and nitrite turns into nitrate.

In normal amounts nitrate is not harmful to your fish, but most fish tank ecosystems aren’t efficient in processing nitrate, and thus nitrate levels tend to build up.

Having high levels of nitrate will stress out your fish, hinder their growth, and lead to a higher susceptibility to diseases and poor color development.

Routine water changes, however, will control nitrate levels in your tank preventing the problems associated with high levels of nitrate.

Improvement of Water Quality

A balanced aquarium can only be maintained through regular water changes, which help physically remove and dilute harmful substances and restore healthy nutrients.

Proper light intensity is needed for the healthy growth of photosynthetic corals and invertebrates, so a water that’s not clear will not promote growth, leading to discoloration.

Besides improving water clarity, routine water changes will also help deliver minerals, vitamins and other nutrients to your fish.

Your filter will remove them and so do the residents in your tank who need them to grow, but water changes will replenish lost nutrients and minerals offering a constant supply just like they would have in the wild.

Removal of Decaying Waste Materials

Decomposing waste materials in your water cause poor water quality by releasing toxic chemicals, phosphates, and toxic nitrogenous products.

Decaying materials can tamper with the buffering capacity of your water throwing off the pH balance and creating an acidic environment.

Now that you’re up-to-speed with the many benefits of cleaning your aquarium, let’s see how it’s all done in practice.

How to Clean Your Fish Tank?

Cleaning the fish tank involves the following steps:

  1. Preparing the water;
  2. Preparing the tank;
  3. Cleaning the sides of the tank and cleaning the decorations;
  4. Siphoning the water and cleaning the substrate;
  5. Rinsing the filter media;
  6. Adding the new water.

Before I discuss each step in detail, I’ll go over the equipment you’ll be needing to clean your tank:

And if you’re cleaning a saltwater tank, you’ll also need:

  • Salt mix;
  • pH testing kit;
  • Refractometer, salinity probe or hygrometer;
  • Powerhead and heater.

If you have all your equipment ready, you can start preparing the water.

Step 1: Prepare the new water

The process of preparing the new water you’ll be adding to the tank is different for freshwater aquariums and different for saltwater aquariums.

Here’s what you should do if you have a freshwater aquarium:

Prepare the water a day before adding it to your tank. If you’re using tap water, you’ll need to add water conditioner to get rid of heavy metals, chlorine or other undesirable ingredients that can harm your fish.

A good idea is to fill up your bucket and allow the water to “breathe” so that chlorine can evaporate from it. Letting the water sit will also get it to room temperature.

Preparing the water is more complicated if you have a saltwater aquarium:

For saltwater tanks you’ll need to observe water salinity, pH and temperature.

For this process, you can’t use tap water and you’ll have to use reverse osmosis water, which is deionized. Test for total dissolved solids to see if it’s under 10. A reading of zero would be ideal.

Next, create the saltwater mix by adding the salt to the water and using the powerhead to keep mixing the salt and circulating the water.

Make sure you add the salt to the water and not the water to the salt to prevent water from turning milky.

Next, set your water heater to 80 F and let it like stay overnight until the salt fully dissolves and the water stabilizes.

The following day, you can start preparing the tank.

Step 2: Prepare the tank

Before you can clean the sides of your aquarium, you’ll first need to:

  • Position your water heater (if you’re using one) so it stays fully submerged during the siphoning of water (if not it could crack or overheat);
  • Turn off your filter if there’s a risk of getting into the filter tube.

Now, you’re ready to do some cleaning.

Step 3: Clean the Aquarium

They key to successfully cleaning the tank is to use the right materials, to be gentle and minimally invasive.

It’s also best if you do the cleaning before you remove the water, so you can remove debris and algae with the gravel siphon and avoid the spread of algae.

To clean the sides of the tank and the decorations, I advise you against using a kitchen sponge however tempted you may be.

Kitchen sponges can contain chemicals or detergents that are no good for your fish.

Instead use an algae magnet or pad and gently run it across the sides of the tank making sure you’re scrubbing as little as possible. Make sure not to scratch your aquarium.

You can gently scrub your decorations with an algae pad. You can remove them if it’s necessary but avoid using bleach or boiling water to clean them because you’ll more than likely kill of beneficial bacteria.

Step 4: Siphon the Water and Clean the Substrate

Get a dedicated bucket to siphon the water out and in the meantime go through the gravel to gently suction out any waste.

If you have sand in your tank, avoid disturbing the sand by holding the vacuum an inch from the surface to suck up the waste.

If you’re worried about sucking up little fish from your tank, place a new stocking on the siphon, which allows debris to enter.

Siphon at an angle to allow substrate to slide back out and to avoid clogging.

Siphon about 10-15% of the tank water into the bucket.

Go slowly while you’re siphoning out the water and vacuuming the substrate giving your fish time to adjust.

Also, don’t throw away the water you siphoned out, you’ll need it in the next step.

Step 5: Rinse the Filter

Before you get the idea to replace the filter, let me stop you: You shouldn’t replace the filter media each time you clean the tank because you’ll mess up the water chemistry in the tank.

A new filter media will remove too much bacteria and upset the water chemistry, which in turn, will send your fish into shock.

So, stick to replacing the filter only monthly or whenever it’s recommended for the type of media you use.

Generally, mechanical filters need cleaning every month, chemical filters every 3 to 4 weeks, while biological filters don’t need much cleaning at all.

A good way to minimize the sudden effects of a new filter is to keep it with the old one for a few weeks until beneficial bacteria colonizes the new filter as well.

So, for the purposes of cleaning the tank, a simple rinse of the filter will do just fine, but DO NOT use tap water to rinse it, instead use the dedicated tank water bucket to rinse it.

Step 6: Add the New Water

Again, here you’ll have to follow different procedures for freshwater tanks and saltwater tanks.

For freshwater tanks:

Measure the temperature of the new water to check if it’s in the range recommended for your fish. A sudden surge or decrease in temperature can kill your fish.

Slowly add the new water to the tank, leaving enough space between the water and the top of the tank for oxygen and carbon dioxide exchange.

For saltwater tanks:

Before you can add the new water to the tank, you’ll have to perform a salinity test using a hydrometer, refractometer or a salinity probe.

If you get a reading between 1.020 and 1.025, the water is good.

Next, check to see if the water temperature and pH are in the recommended range. If it’s all good, you’re good to go.

It’s a good idea to get a water pump with a 10 feet flexible tubing that can push the water at least 5 feet high if you’re struggling to lift the bucket to the side of the tank.

Extra Step: Clean the Outside of the Aquarium

While you’re at it, give the outside of the tank a little cleaning too. This is not an obligatory step, but it will make things look nicer.

Regardless of whether you’re cleaning the inside or outside of your aquarium, use only tools and solutions that are designed especially for aquarium cleaning.

Using inadequate tools can harm your fish.

To Summarize…

Beginner aquarists start out with the notion that fish are not maintenance-intensive.

While it’s true that you don’t have to clean their litter each day or take them for a walk in the park, you do have to look out for them too.

Like other pets, fish too require care in the form of feeding and cleaning their tank on a regular basis.

Cleaning a fish tank is not that difficult and it can be done in the six easy steps I described above regardless of the type of aquarium you have.

You can even teach your kids to do it too, so they’ll be able to take over after a while and clean the tank themselves or help you out with it.

Make sure you go over all the parameters of the water (temperature, pH, salinity, and others) and use the right tools to carry out the tank maintenance.

It’s important to regularly clean your fish tank, and I recommend doing 10-15% water changes weekly.

Others might say to clean your tank every other week and maybe do a 20-30% change, but it all depends on how big your tank is, what kind of filtration methods you’re using, and how many fish you’re keeping.

I’d say you should err on the side of caution and do it weekly, and with time and more experience you’ll be able to tell how often it needs cleaning just simply by monitoring your tank daily.

I hope this guide has eased you into the process of tank maintenance and has answered most of your questions about cleaning aquariums.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.

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