How To Clean Fish Tanks – The Importance Of Regular Cleaning

The least exciting part of owning an aquarium is dealing with the routine maintenance. But knowing how to clean a fish tank or bowl will save you time and money in the long run. A well-maintained tank is usually a healthier one that suffers from fewer problems.

It’s a lot easier to clean your tank than you might think, and it doesn’t take any special skills or expensive equipment, either. In this DIY tutorial, I’ll show you step-by-step how to clean an active aquarium of any size!

Common Questions About Aquarium Cleaning

Before I dig into the details and toss out lists of the equipment you’ll need, let’s take a second to discuss why routine cleaning is so important to the health of your tank and the species inside it.

Why Do We Clean Aquariums?

The most important step of your tank maintenance routine is doing regular water changes. Since an aquarium is a closed system, fish waste and other debris accumulate in the water. If you don’t remove and replace some of the water in your tank at regular intervals, these debris break down and poison your tank.

A filter can help remove physical debris and neutralize toxins to a limited extent. But they can only give you extra time between water changes and don’t replace regular maintenance. You’ll still have to keep up on your algae removal, maintain your filter and know how to clean fish tank gravel as well.

What Does It Mean To Clean An Aquarium?

Cleaning is a rather broad term and encompasses a lot of different tasks when it comes to maintaining an aquarium. I tend to speak of specific actions, like doing a water change or vacuuming the gravel over using the term “clean.” When you clean your aquarium, you’ll do a partial water change at the very least.

Depending on the conditions in your tank, you may also need to change the filter pad and/or filter media, vacuum the gravel or remove any algae growing on the tank sides or decor. But don’t take the cleaning too far. You can actually cause a tank to crash like a new tank if you clean it too thoroughly!

You’ll also want to clean the outside surfaces. Once a month you’ll want to polish your glass or plastic tank and dust-off the aquarium hood, lighting fixtures and any equipment tubing or cords running into your set-up.

How Often Should You Clean Your Tank?

Unfortunately, there’s a lot of variables involved. I can’t give you a hard and fast answer. You’ll have to work out a schedule for your tank based on its unique characteristics.

The frequency of aquarium water changes and cleaning depend on:

• The size of your tank and the type and density of the inhabitants
• Whether you’re using a filtration system and what type of filter you have
• The location of your set-up and how much light the tank receives

In general, you’ll need to do water changes and clean your tank at least once a month for larger set-ups and as often as several times a week for smaller ones. Here are some guidelines:

How Much Water To Swap For A Routine Water Change?

Routine water changes usually involve removing and replacing a small percentage of the water in your tank. 10% – 25% is a typical amount to replace, but if your aquarium is especially dirty a 30% to 50% change may be needed. I don’t recommend changing more than 50% every 24-hours to avoid stressing your fish.

If you have problems with a foggy fish tank or an extreme algae or cyanobacteria outbreak that isn’t helped by routine water changes, you’ll want to assess your equipment and water quality, and possibly seek professional advice.

Do You Have To Remove Fish To Clean A Tank?

No, you don’t have to remove your fish from the tank to clean it! If you have a very small fish bowl it may be helpful to put your fish in another container for cleaning, but I’ll teach you a method below that’s even easier. For larger tanks over 5-gallons you shouldn’t worry about removing them. You’ll clean around them instead!

How To Clean Aquarium Rocks And Decor?

Occasionally, you may find it easier to take out an algae-encrusted rock or decoration and give it a scrub down with a pad and plain tap water. If this is a constant problem, however, you should consider adding algae-eating aquarium species like snails or freshwater shrimp, or reduce the amount of light your tank receives.

Special Considerations

This tutorial is primarily aimed at fish keepers with existing freshwater set-ups rather than those setting up new tanks, problem tanks or maintaining 500-gallon saltwater reef tanks. I recommend seeking out detailed advice for your particular situation, but I’ll touch on them briefly here.

New Aquariums

New set-ups can be a bit frustrating, as it takes time for your aquarium substrate to settle and your tank to cycle so you avoid “new tank syndrome.” This is a whole topic in and of itself.

You shouldn’t add fish to a new tank right away, although the amount of time you’ll need to wait depends on the size of the tank, the type of substrate and the heating and filtration systems. It takes time for healthy aquarium bacteria to establish themselves in your tank and you may need to do extra water changes too.

I recommend waiting at least a few days and then adding new fish gradually over the course of a month rather than adding a lot of fish at once.

How To Kill Algae In Aquariums

Most tanks will eventually see some algae growth. Algae takes advantage of the light and the nutrients from the fish waste to spread. Regular water changes should keep its growth under control, so you don’t need to work to eliminate it entirely.

If you have algae-eating aquatic species, you’ll need some algae to feed them. If you have a problem with algae that water changes and algae-eaters can’t control, try moving the tank out of direct sunlight and reducing the amount of light it receives.

You can also manually remove the algae from the sides of your tank with a special glass or plastic-safe scrubbing pad or magnetic aquarium scraper. I keep these on hand to remove excess algae from my tank during my monthly maintenance routine.

How To Clean A Plastic Fish Tank

Aquariums are most commonly made from glass, plexiglass or plastic. Be sure that any scrubbers or gravel vacuums you have are safe with your type of tank. This isn’t really a problem with gravel vac’s, since they are usually plastic themselves. But a scrubber made for a glass tank could scratch a plastic aquarium, so be careful.

Other than trying to avoid scratches on your tank, cleaning a plastic tank is just like cleaning a glass one. Never use bleach, soap or other cleaners on any type of aquarium or decor, plastic or glass. Plastics and the silicone sealant used in glass tanks may absorb the cleaner and release it into your water, which can be toxic.

Hard Water Aquariums And Saltwater Fish Tanks

In most ways, changing the water in a saltwater tank is similar to a freshwater set-up. You’ll use the same equipment to remove and replace water. But you’ll also be managing salinity levels in a saltwater aquarium, and dealing with something called salt creep.

Salt creep happens when the water evaporates from your saltwater tank. As the water splashes out of your chiller or filter it creates a mist of salt spray that can dry and encrust your equipment. If not regularly removed, the salt will build up and corrode or damage your lighting fixtures and other equipment.

This problem is also common for freshwater aquariums in areas with very hard water. The minerals in the water act a lot like salt, and form a crust on your tank and equipment. You have to gently scrape the salt or minerals away while you do your regular routine maintenance.

Equipment Needed To Clean An Aquarium

There’s a lot of equipment available online for cleaning an aquarium, but what do you really need? You can even use vinegar for cleaning. Equipment needed depends on the size of your set-up. I’ve broken my lists down into 3 categories based on the size of the aquarium you’re cleaning.

While you can certainly use the list and instructions I recommend for one size tank on another, it may not be ideal. Trying to change a 10-gallon tank of water using my method for a fish bowl would take forever!

Cleaning A Fish Bowl Or Tank Under 5-Gallons

What do you need to regularly change the water and clean a small fish bowl? Not very much, as it turns out. These small bowls are usually easy to pick-up and move, so you can change the water right by your kitchen or bathroom sink!

I’ve included two different techniques for cleaning fish bowls because my preferred method (the second technique) won’t work with extremely small tanks. For those, you’ll want to use the first list and method as outlined below.

Equipment Needed—1st Fish Bowl Cleaning Technique

If you have an extremely small set-up such as a half-gallon betta bowl (not recommended), you may find it easier to move your fish and half of the water to another bowl before cleaning it. In that case, you’ll need:

1. A dedicated glass or plastic container big enough to hold your fish and about half the water in your tank. If you opt for a plastic bowl, use it only for fish and never clean it in a dishwasher or using soap, bleach or other chemicals.
2. A small fish net to catch and move your pets from bowl to bowl.
3. Appropriate water conditioner to neutralize chlorine, chloramine and other chemicals in your tap or aquarium water (such as ammonia).
4. Small scrubbing pad to remove algae or hard water deposits.
5. Optional: A new, fish-only turkey baster never washed in soap, bleach or chemicals.

Equipment Needed—2nd Fish Bowl Cleaning Technique

For this second technique, you’ll leave your fish in the original bowl and clean around them instead. You’ll need:

1. A small cup or ladle to transfer water from tank to sink. A cheap turkey baster used only for your routine cleaning can work as well and is very useful for picking up physical debris from the bottom of the bowl without risking injury to your fish.
2. Appropriate water conditioner.
3. Small scrubbing pad.
4. Optional: If you can’t bring your bowl to a sink, use a dedicated glass or plastic bowl to transfer water between the fish bowl and sink instead.

Cleaning A Small 5 to 10-Gallon Tank

While you can move a small fish bowl, it’s a lot harder to move a small aquarium. A 5-gallon tank may easily surpass 60-pounds in weight once you account for the substrate and water. For changing water in these set-ups, you’ll need a bit more equipment:

1. A simple gravity-based siphon and hose with a gravel vacuum tip.
2. A dedicated bucket used only for aquarium maintenance and never cleaned with bleach, soap or other chemicals. Pick one with a comfortable handle and handy pour spout that has a 3 to 5 gallon capacity.
3. Appropriate water conditioner.
4. Aquarium-safe scrubbing pad sized to fit your tank.

Cleaning A Large Tank Over 10-Gallons

The bucket-and-gravity-siphon method works great for tanks up to 10-gallons in size. But I doubt anyone would want to lug 25-gallons of water or more in buckets! Instead, for bigger aquariums I recommend investing in a vacuum system that moves the water in and out using the water pressure from a nearby faucet.

You’ll need enough hose to reach between your sink and the aquarium, but you won’t have to move buckets around. These devices can be tricky at first to figure out because you may need to customize the set-up so it works with your faucet. For cleaning a large tank you’ll need:

1. Faucet-attachable adapter with enough hose to reach your aquarium and a gravel vacuum tip on the end. These are often referred to as powered or no-spill gravel vacuum systems.
2. Appropriate water conditioner.
3. Aquarium-safe algae scrubber.

Step-by-Step Instructions—How To Clean An Aquarium

All you have to do is pick the method that’s best for your tank based on its size and follow the instructions! While you can use any of these methods to clean any sized aquarium, I’ve matched each technique to the amount of water you’ll be playing with.

How To Clean A Fish Bowl: 1st Technique

If your fish bowl is very small or has a narrow opening, you may not have enough room to fit a cup or ladle inside to transfer water out of the bowl. Instead, you’ll use another vessel to hold your fish and some of its water while you clean the bowl.

Always remove any filtration systems and unplug any heaters you’re using before you clean a fish bowl. It may take a few minutes for your heater to cool as well, so be careful and have a safe place to put it while you clean.

Step 1: Move Bowl And Place Next To Your Kitchen Or Bathroom Sink

Carefully move your full fish bowl and place it on the counter next to your sink. Get out your equipment and prepare to start cleaning! Alternatively, if it isn’t convenient to move the bowl while it’s full of water, you can skip this step and move to Step 2 instead.

Don’t forget to wipe down the lid or hood to your bowl with a damp rag, and scrape away any harder stuff with the scraper.

Step 2: Transfer Water From Fish Bowl To Temporary Bowl

Carefully pour some water out of the fish bowl into your temporary vessel, or use the turkey baster to move the water from one to the other. Be careful not to pour your fish out along with the water, because that could cause an injury or stress your pet.

You’ll need to remove at least a cup of water so your fish will have enough to swim in as you clean the fish bowl.

Step 3: Transfer Your Fish To The Temporary Bowl

Using the fish net, catch your fish and gently transfer them into the temporary set-up. Once you do, examine your fish bowl and see if the decorations or sides of the bowl need to be scrubbed too. If so, you can gently wipe the algae off with a scrubbing pad now.

Step 4: Place Fish Bowl In the Sink Under The Faucet

Gradually turn the water on until it’s pouring into your bowl with enough force to stir the substrate a little. You don’t want to disturb the substrate entirely or destroy any good bacteria that lives in it. You want just enough water flowing in to lift debris from the top of the substrate and over the side of the bowl.

Allow the water to flow for a minute or two, until visible debris have been flushed from the top of your substrate.

Step 5: Adjust The Water Temperature And Refill Your Fish Bowl

Once your bowl is clean enough (and for multi-week cleanings you don’t need to have a perfectly clean bowl) adjust the water temperature to match that of water in your temporary bowl. Allow the fish bowl to refill, leaving room for the water and fish in the temporary bowl.

Step 6: Add Appropriate Amount Of Water Conditioner

Once your fish bowl is cleaned and refilled, follow the instructions on your brand of water conditioner and add the correct amount to the water in the fish bowl. If you partially emptied your fish bowl prior to moving it to the sink, return it to its original location before adding the water and fish back in.

Step 7: Return Your Fish And Water To The Bowl

Using your fish net, gently catch your fish and transfer them back to your fish bowl. You can carefully pour the water from the temporary bowl into the fish bowl or transfer it with the turkey baster, being cautious not to disturbed the substrate or decorations. Return the fish bowl to its usual location and you’re done!

How To Clean Fish Bowls: 2nd Technique

For wider or bigger fish bowls, you shouldn’t have any trouble fitting a plastic cup, soup ladle or even a turkey baster inside. With this method, it may be easier to leave your fish bowl in place and use another dedicated bowl to take the waste water to the sink and bring fresh tap water back.

If you’re not moving your fish bowl, you can leave the filtration system in place but you should still unplug and remove the heater. This will give you more room to fit a cup or ladle inside and removes the risk you might accidentally hit and break your heater.

Step 1: Transfer Water From Fish Bowl To Transfer Bowl

Stir the substrate a little to raise the debris from the bottom of the bowl, and move the decorations if there’s a lot of material hiding under them. Lower a cup or ladle into your fish bowl and scoop out some of the dirty water. Be careful not to scoop up your fish too!

You can remove a little bit of water or up to half the bowl if it’s really dirty. If there’s a lot of debris in your bowl, consider targeting them with the turkey baster rather than just scooping water with the ladle. Dump the waste water in your transfer bowl as you clean.

Step 2: Check The Sides Of Your Bowl And Decorations For Excess Algae

If you need to remove algae, use an appropriate scrubber to wipe it from the bowl or your decor. A bit of algae in a fish bowl isn’t a concern but if you don’t have an algae eater you may want to be a bit more on top of this so it doesn’t get out of hand.

Don’t forget to wipe down the lid/hood to your bowl with a damp rag, and scrub any parts that need it. You can do that in a sink if it’s easier.

Step 3: Dump The Waste Water And Adjust The Faucet’s Water Temperature

Dump the dirty water in a sink (or use it for your houseplants or garden!). Turn the faucet on and adjust the temperature until it matches the water already in your fish bowl. Rinse the temporary bowl and refill it with the warm tap water.

Step 4: Add Appropriate Amount Of Water Conditioner

Following the instructions on your bottle, condition the water in the transfer bowl and return to your fish bowl. Careful pour the water back in or transfer it gently using the turkey baster. Try not to disturb your substrate too much. Replace the heater in the tank and plug it in, and turn the filter back on as well. You’re all done!

How To Clean Small Aquariums

While you can carry your fish bowl straight to your sink, for tanks bigger than 5-gallons you’ll need to use a bucket to move the water to and fro. You’ll also have to stick your hands in your aquarium. You can also opt for the method I use for larger tanks, but it might be overkill for a small 5-gallon set-up.

I recommend washing your hands and arms with hot, soapy water and rinsing them well before you start. This will remove the oils and any bacteria from your skin, along with lotions, perfumes or other things that could contaminate your tank. I do this any time I need to reach into my aquarium, and it’s a good habit to get into.

Step 1: Examine Your Tank, Remove Algae And Prune Plants

Get all your equipment ready before you start. Examine your tank for dirt, grime, white spots etc so you know what kind of extra cleaning you’ll need to do. Remove the lid and turn off the filtration system and heaters. If your tank is quite small, you may want to remove the heater as you clean, but that’s optional.

Use a scrubbing pad or magnetic glass cleaner to remove any excess algae from your tank’s side. You can scrub off plastic plants or rocks and decorations as well, if needed. It’s better to simply remove the leaves from any live plants that are overgrown with algae. You can prune your plants for healthier growth as well.

Step 2: Arrange Siphon And Bucket By Aquarium

Place the siphon or gravel vacuum in your aquarium with one hand. Aim the end of the hose towards your bucket with your other hand. Prime the siphon as directed and water should move via gravity from your tank into the bucket. It’s handy to have a clean towel nearby to dry your hands on, as well.

Step 3: How To Clean Fish Tank Gravel While Changing Water

As the water pours into the bucket, use the gravel vacuum tip to carefully remove debris from the substrate in your tank. You’ll see the dirty water flowing through the siphon. Concentrate on the areas around plants and decorations, as this is where the bulk of the debris are likely hiding.

Try to avoid picking up your substrate along with the debris. This is usually more of a problem with lightweight sand rather than gravel or rocks. Also, be careful you don’t accidentally pick up your fish or invertebrates!

Step 4: Empty The Waste Water

Once your bucket is filled, stop the flow of water so you can empty it. Some siphons have a switch to close the line so you don’t have to break the suction. You can always remove the siphon and vacuum tip from the water to stop the flow, but you’ll have to prime it again to restart the flow.

You may need to make several trips to dump dirty water from your tank. It just depends on the amount of water you’re changing and size of your bucket. You’ll be aiming to remove roughly 10% to 30% of the water in your tank and don’t have to be precise.

Step 5: Adjust Your Water Temperature

Before you can start filling up buckets of water to refill your tank, you’ll need to adjust the temperature to match that of the water in your tank. I find it’s easier to add the correct amount of water conditioner to the tank right before I start refilling it, rather than conditioning each bucket individually.

Step 6: Refill Your Tank

Using the warm water from your faucet, refill your bucket and bring it to your tank. Gently pour the water into the tank, trying not to disturbed the substrate too much. You can place a small ceramic plate in the tank to disperse the water if you prefer. Once your tank is full, remove the plate and restart your filter and heater.

Step 7. Clean The Hood And Light Fixtures

Don’t forget to wipe down the lid/hood of your tank with a damp rag, and scrub any parts that need it. You can do that in a sink if it’s easier. Be careful if your lids are glass, and cushion them on sponges so you don’t accidentally crack them.

Using the dry towel, wipe down any spilled water from the sides of your tank. Replace the hood or lid. That’s all you need to do until your next water change!

How To Clean Large Aquariums

The main difference between cleaning a small aquarium vs a larger one is the way you transfer the water. It just isn’t very practical to use buckets for bigger capacity tanks. Instead of using a gravity siphon, invest in a gravel vacuum that attaches to your kitchen sink. You should still give your hands and arms a good wash first.

These “no spill” systems use a special faucet adapter and system of hoses. The pressure of water moving out of the faucet creates suction in your hose. When you place the gravel vacuum tip in the tank, it will pull the water out and send it down the sink’s drain. No buckets and less mess!

Step 1: How To Remove Algae From Fish Tanks

Just like for smaller tanks, you should get all your equipment ready before you start. Examine your tank and look for algae to clean. Remove the lid and turn off the filtration system and heaters. You shouldn’t need to remove the heater but be mindful of its location so you don’t accidentally break it.

Use a scrubbing pad or magnetic glass cleaner to remove any excess algae from your tank’s sides. You can scrub off plastic plants or rocks and remove the leaves from any live plants that are overgrown with algae.

Step 2: Set Up Your Gravel Vacuum And Faucet Adapter

Hook up your gravel vacuum and test out the adapter both open and closed before you start. You don’t want to discover partway through that you need to make adjustments, because this could send water all over your countertops. Place the gravel vacuum tip in your tank and secure it with a clip.

Go back to your sink and turn the water on, leaving the adapter open so water goes into your sink and down the drain. You should quickly see water moving down the empty hose from your aquarium. Once you’re sure it’s working, return to your aquarium.

Step 3: Vacuum The Gravel As You Remove Water

Similar to Step 3 for smaller aquariums, move the gravel vacuum tip through the top layer of your substrate and around your plants and decorations. Pick up as much of the visible debris as you can without grabbing your fish or other tank occupants. Focus on removing the water from the lower parts of the tank.

Once you’ve removed the percentage of water you’re aiming for, close the valve on the hose near the vacuum tip and clip it to the side of your tank. Return to your sink for the next step.

Step 4: Adjust The Water Temperature

Back at your sink, adjust the temperature until the water coming out of the faucet is the same as the water in your tank. Once it’s ready, close the adapter so this warmer water is forced into the hose towards your tank.

Since the other end is closed the water won’t be able to enter your tank until you open it. So you’ll likely hear the water hiss during this step and the adapter may leak a little or spray some water around your sink. Once you open the valve this shouldn’t be a problem.

Step 5: Open The Valve And Refill Your Tank

Return to your tank and open the valve. Water should immediately start flowing into your tank. Check the temperature as it starts flowing in to be sure it isn’t too hot or cold and adjust the faucet if the temperature is off. For big aquariums you can keep filling as you make fine adjustments to the temperature.

As your tank refills, add in the appropriate amount of water conditioner. Once it’s full, close the valve and remove the gravel vacuum tip from your tank. Carry the tip back to the sink and release the pressure on the faucet adapter. Now open the valve and drain the water in the hose into your sink.

Step 6: Clean The Light Fixtures And Top Of Tank

Clean your lids just as for the smaller tanks in Step 7 above, taking care not to damage any fragile parts. Replace them on your tank. Wipe down your tank and the light fixtures and you’re set!

Conclusion

Cleaning a fish tank is not a tough proposition when you have a step-by-step tutorial to help you through the process! Aquariums are complex systems with many living parts. Algae can be food for your fish and bacteria is necessary to maintain your water quality. You’ll not want to eliminate them entirely.

So don’t worry about how to sterilize a fish tank, which is something I’ve never needed to do. Regular water changes and routine maintenance on your plants, decor and equipment will help everything last longer and keep your tank healthier. This can save a lot of money in the long run because you’ll need to replace fewer fish!

I’d love to hear about your experiences after reading this tutorial. Did you find this article helpful? Tell us about it in the comments, or join us on social media!