Best Filters for Large Aquariums

Do you own monster fish or a large tank? Unfortunately for us, we can’t teach our fish to go outside, so we need to take a look at the best aquarium filters for large tanks to do the work for us.

It’s not just fish waste that can unbalance your water chemistry. Decaying food or organic matter, ammonia, bacteria, and a variety of other factors all play into the mix when you’re trying to create the perfect habitat for your tank.

Larger tanks are lightly insulated by their size. Even when something gets unbalanced or something toxic is introduced into the water, the volume of water in a large tank dilutes it. However, large tanks still experience water problems. The more fish, plants, or live rocks in the tank, the more you have contributing to your waste problem and water chemistry.

Filters don’t just remove waste. They balance out chemicals in the water, kill harmful bacteria, and add beneficial bacteria back into the water. If you have an aquarium that’s over 80 gallons, you have a large tank with a lot of potential for waste buildup. Unless you want to do partial water changes every few days, you need to find the right filtration setup for your tank.

Here’s how.

Aquarium Filter Specs for a Large Fish Tank

Tanks have all the same basic needs and characteristics, but things change a bit when the size of the tank changes. While fish still need well-balanced water, heat, and food, inhabitants of a large tank need a bit more out of their filters. Here’s a rundown of the kind of filter a large aquarium needs:

1. Appropriate Capacity

With filters, bigger is always better. You can’t over-filter your tank water. It’s better to get a very large filter than the get one that’s too small. Filters should be large enough to filter a minimum of around 4 times the size of your aquarium an hour.

It’s better to get a filter that can filter your tank’s gallons 4 times per hour. This means the GPH of the filter should be at least 4 times the size of your actual tank. If you need more power, you can always add another filter to the tank. There’s no harm in having multiple filters for one aquarium. With large aquariums, it’s usually the case. When I first upgraded to a 150-gallon tank, I ran 3 AquaClear 110 filters and a canister filter.

That being said, over-powered filtration has the drawback of sucking up things you don’t want inside your filter. If you don’t have a protective cover, like a strainer, it may accidentally suck up aquarium substrate or small fish. Organizing your tank well and choosing the right tank inhabitants can negate these problems.

2. Filtration Stages

Most large aquarium filters will have all filtration stages (mechanical, biological, and chemical), but you need to make sure the balance is right. Larger tanks need a good balance of biological and mechanical filtration with less of a focus on chemical filtration.

Biological filtration is especially important for maintaining a proper balance in your tank. The larger the tank, the more space you’ll need for biological filter media to keep up. Mechanical filtration is the same, as larger tanks naturally produce more waste that must be filtered out. If you don’t have enough mechanical filtration, you will have to clean your filter very often.

3. Type of Filter

Filters come in many different types. The most common types you’ll see in use for larger tanks are canister filters and HOB (hang on back) filters. These are the two most powerful types of filters.

Other types of filters exist, including under-gravel filters, submersible filters, and sponge filters. However, none of these can handle larger tanks as well as a HOB or canister filter. They don’t have the power necessary to cycle enough water and keep the water clear without having multiple filters for the same tank.

4. Maintenance

Cleaning a filter is never going to be a fun experience, but it can be better for some filters than for others. HOB filters are some of the easiest to clean and change the filtration media. Most of them don’t need frequent cleaning, and cleaning may just involve removing media to wipe out the filter chamber.

Canister filters are notoriously harder to clean. They’re sealed closed and need a lot more effort to get fully opened and cleaned. While they’re not impossible to clean, it can take some getting used to for you to be fully comfortable cleaning your canister filter. The most difficult part is usually opening and closing the filter because you need to re-prime the filter to start it up again.

5. Practical Considerations

Along with all the actual filtration and power, you have to think about how a particular filter fits in with your tank practically. Look at the dimensions to know if it will fit well with your tank setup and see what kind of space it needs in and around the actual tank to do its job.

Placing the filter isn’t the only thing you have to look at. Filter setups require different amounts of space at the top of the tank to work, including some cutouts that give space for the filter or its tubes. Canisters use two different tubes, so they don’t require a large cutout space in the tank lid. This helps you seal the tank closed to keep your fish, snails, reptiles, crustaceans, and other inhabitants inside.

HOB filters need a large space cut out of the top of the tank lid to operate. This leaves more room for water evaporation and opens a potential escape route for tank inhabitants.

6 of the Best Aquarium Filters for Large Aquariums

1. Fluval FX6 Canister Filter

The FX6 is a large, black cylindrical filter with red accent pieces. It measures 16 x 16 x 21 inches, so it does take up a bit of space wherever you put it. Input and output valves on top of the filter take up a few extra inches of space above the filter. However, it’s still compact enough to fit under many tanks and cabinets.

Inside, the 3 filter media baskets hold a total of 1.5 gallons of different media. This filter takes loose media of any kind, though you can also find some sponge filters and filter pads that fit the baskets. The baskets fit well to prevent water from bypassing the media.

After hooking up the filter and adding in the media, you’ll just add water to the inside and turn the filter on. This filter is designed to self-prime. No siphoning is required to get it working. You can adjust the flow rate with knobs on top of the filter.

To open the filter up, unscrew the tabs around the side and lift the lid. It’s fairly easy to access to inside for cleaning and maintenance. Intake and outtake hoses on top are telescopic and are simple to remove when necessary.

2. Penn Plax Cascade Canister Filter

The difference between the regular models and elite models is that the elite filters come in a set. Each set includes 4 different types of filtration media, hoses, valve connectors, and everything else necessary for setting up the filter. An algae magnet for cleaning tank glass is also included.

This canister filter has a more rectangular shape. It measures 11.5 x 20.5 x 12 inches in size. Both hose valves attach on top of the filter, adding a few inches to the overall height once it’s set up.

In the largest version of this filter, you get 5 interior baskets to fill with media. They’re designed to be air-tight to keep water from bypassing filtration media. You can use any combination of filter media you want within the baskets, including sponges or pads sized to fit the baskets.

While this pump doesn’t self-prime when turned on, there’s a simple priming button to get it started. It will hold its prime until it’s opened again, even if the power cuts while it’s running.

3. Hydor Professional External Canister Filter

This Hydor canister measures 11 x 9 x 24 inches. Telescopic valves on top of the filter add a few inches to the overall height of the canister as well. It’s designed well to fit into tighter spaces, and the shape is easy to get into cabinets.

This kit comes with all the necessary pieces to get the filter set up right away. There’s filtration media, hoses, hooks, valve heads, and more.

In the 600 models, there are 4 filter media baskets that sit on top of each other inside the canister. You can use the included filtration media or buy your own loose media and sponges or filter pads to fill up the spaces.

You will have to prime this filter as you set it up. First, establish a good siphon to suck water into the intake hose. Then, you can press the priming button a few times to help the motor purge the remaining water and turn it on.

4. Fluval G6 Advanced Filtration System

A built-in viewing screen on the front helps you adjust the flow rate and view information like the water temperature. This is a useful feature for more precise adjustments and quicker information.

The lid on this canister seals closed with 4 large tabs around the corners that lock it down. Inside, 3 large media baskets sit on top of each other. There’s space for large amounts of loose media of all kinds.

Although it’s close, it’s not a perfect square. The actual dimensions of the larger model are 10 x 9 x 13 inches. It’s significantly shorter than many other large canisters, making it fit more easily underneath cabinets around your tank. This filter has hose intake and outtake valves that connect to the top of the lid, making it a few inches taller when fully set up.

You will need to prime this using the priming button located on top of the canister. It is not a self-priming unit.

5. Fluval 406 External Filter

Inside, this filter holds up to 2.25 gallons of filtration media within 4 baskets. Smaller models have fewer baskets. Baskets are fitted well to prevent most water bypass.

The Fluval 406 measures in at 7.6 x 14. x 17.8 inches. It’s a tall, skinny rectangle that’s relatively easy to fit around most aquarium setups. Water valves do add a few inches onto the top of the canister.

Although it’s not a self-priming filter, it holds its prime even if it goes off from a power outage. As long as you don’t open the filter, it will stay primed. Each time you open and reseal it, you will prime it again using the top button.

6. MarineLand Magniflow Canister Filter

In the larger version, the flow rate reaches up to 360 GPH. At this larger capacity size, it measures 10.75 x 13.38 x 17.25 inches. There are a few inches of added height on top because of the water valves located on the top.

There are 4 baskets inside to hold filtration media. Filter media is included in the kit to help you set up the filter as soon as you get it. The flow rate is not adjustable on the filter.

You can prime the filter using the priming button on the top of the filter. It will usually stay primed even when it’s turned off until the top is open. Priming is easy and can be done at the push of a button.

Sump Filtration for Large Aquariums

Can I use a sump to filter a large fish tank?

Yes, you can use a sump to filter any size of the tank. Large tanks work well with sumps because they help you keep all the equipment out of the way while giving you a little room for error with the water parameters.

If you have a saltwater tank, especially a reef tank, it’s highly recommended to use a sump tank. You can get by without one in a freshwater tank, but saltwater tanks take more water maintenance and a sump allows you to regulate everything more easily.

Although a sump filter sounds complex, it’s much simpler than you might expect. In the most basic terms, a sump tank is a smaller tank that you connect to your main aquarium to help regulate the water conditions. Sumps work in the same way as canister filters or other pieces of equipment that draw in tank water, modify it, then return it.

In the case of a sump, it’s just larger than individual equipment pieces and works as the all-inclusive area for equipment. Filtration, heating water conditioning, protein skimming, and everything else can be done to water while it’s in the sump. When the water from the sump is taken back to the main tank, it will be clean and temperature regulated.

Why Use a Sump Tank?

There are a few benefits you can get from a sump tank:

1. Increased water volume

Sumps add extra gallons to the total tank water. You’ll be less likely to experience catastrophic system failure or huge variations, as everything will be more diluted. This gives you a lot more control over what happens with your tank water so you can react to problems before they do any real damage to your aquarium.

2. Aesthetics

Most tank equipment doesn’t look nice. If you use a sump tank, you can put all the ugly equipment inside the sump instead of the main tank. It’ll work just as well and won’t be visible at all. You can also put your tank in a location it may not have fit in before because you won’t need a lot of clearance around it for a HOB filter, heater, or otherwise. You’ll also be able to cover the top fully.

3. More choices in-tank equipment

Since you won’t be limited by what’s already in your main tank, you’ll have more options for what you want to use in your tank. Your sump doesn’t have to look good, and there’s no issue with the substrate, fish, plants, etc. It’s important to note that you will have some limitations with a sump, such as not being able to use a canister filter, but these limitations are replaced by other options.

How Big Should an Aquarium Sump Be?

Sumps can vary a lot in size. You don’t want the sump to be larger than your actual tank, but it should be large enough to contain any water left in pipework or tubing without overflowing. Most people do not fill their sump tanks all the way so that the sump can contain any extra water in case of power failure.

As a rule of thumb, it’s recommended that a sump should be at least 25% as large as your main display tank. So, if you have a 100-gallon tank, your sump should be at least 25 gallons. Along with the gallons, you need to consider the equipment you’re using. The sump should have enough space for everything you’re using in your tank. It should be too crowded, or the equipment won’t have enough contact time with the water to maintain it well.

Sumps that are 25% as large as your main tank will usually work out well for large aquariums. But, the most important thing to think about is how much space you have. You won’t be able to have a larger sump if you don’t have the space to fit it around your tank. So, that limitation has to be considered.

What Kind of Filter Can You Use in a Sump Tank?

Sump tanks don’t use traditional filtration. While you can hook up a power filter to it, it’s not recommended because it wouldn’t work as efficiently as a customized sump filter. Instead, you can use the whole sump as a filtration tank. But adding a few dividers within the sump, you can create filtration chambers that can hold a lot of filter media.

Dividers can be put anywhere within the sump as long as they’re sealed in place to prevent water bypass. Each divider will have a hole drilled in it to allow water to go to the next filter section. Each section is full of different types of media, with a focus on biological and mechanical. You can look up designs and instructions to follow to make your own custom sump filter, or you can buy a pre-made sump and just fill it with media.

You cannot use a canister filter with a sump tank. Because canisters take water out of the tank to filter it, there would be a water flow problem and some of the water may never reach the filter. It’s a better idea to have a full sump filter instead.

Can You Use a Sump for Freshwater or Saltwater Tanks?

Saltwater tanks are the main aquariums that you find hooked up to sumps. However, that doesn’t mean you can’t use one for a freshwater tank. You can use a sump tank with any type of aquarium, no matter what kind of water it holds or what kind of live inhabitants it has.

While a sump tank may not make sense for a smaller freshwater tank, it can help you a lot with a large tank. You’ll get great filtration and it will be easier to maintain healthy, clean water.

Most saltwater tanks benefit from a sump, even the smallest tanks. If you have a large saltwater tank, you should definitely look into having a sump tank. It’s easy to connect a sump to a protein skimmer to tackle two filtration steps at once.

Sump tanks aren’t necessary for everyone, but they’re a bit easier to manage than some of the larger filters and they offer a lot of benefits. You do need to have more space to make it work, which might make it impossible for some setups. Look at your own needs and see if a sump makes sense, or if you’re better off sticking with a pre-formed filter.

Related Questions

How much filtration is needed for large tanks?

As a rule of thumb, any tank should have a filter with a flow rate at least 3 times as large as the size of the tank. If you can get filtration that’s 4 times the tank size, that’s even better. Always err on the side of too much rather than too little. You can’t over-filter the water, but you can under-filter it.

It’s good to note that your tank might need more filtration if it’s heavily loaded versus lightly loaded. Large reef tanks with fish need stronger filtration than freshwater planted tanks with fish. The more fish and other life you have in the tank, the stronger the filtration should be.

Does sand get caught in large filters?

Filters that are very strong may have a problem sucking things up from the tank. If you’re using tank sand and the filter water intake hose is too close to the bottom, sand and other small substrates can get pulled into the filter.

You can help prevent this by putting a straining screen over the filter intake. A thin mesh screen can keep sand and substrate out of the filter without hindering its flow. It may also keep tiny fish from getting sucked into the filter, which is another common problem for larger filters.

Is a UV light filter necessary for clear water?

Sometimes. UV lights are strictly necessary for clear water, but they kill a variety of pathogens and algae that grow in tank water and affect clarity. A UV sterilizing light in your filter can improve water clarity, but only in certain cases. It won’t help clear up all causes of cloudy water.

Conclusion

Choosing the best aquarium filter for large tanks comes down partially to preference. There are a lot of options, none of which are perfect choices for every tank. Think about your setup and look to see which filter might work best with what you’ve got.