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If you want to reduce or eliminate the need for water changes altogether, an aquarium sump can help you to do that and is a brilliant feature if you want a low-maintenance setup.

The sump sits underneath the aquarium and provides additional stages of filtration, as well as performing other basic maintenance functions. Sumps are very versatile, ranging from single to multichambered setups and small to large versions.

In this guide, we explain more about how aquarium sumps work and show you how they can benefit both novice and expert hobbyists. But first, here are five great aquarium sumps for you to consider.

Top 5 aquarium sumps

In this section of our guide to aquarium sumps, we review five of the best sumps that are available on the market today. We’ve included links to the relevant information on Amazon.com so that you can read the full product specifications, as well as checking out reviews left by other people who have bought the sumps.

Once you’ve chosen your preferred product, simply click on the in-text links provided to place your order.

1. Eshopps Wet Dry Sump Filter

Eshopps Wet Dry Sump Filter is a great place to start for those who are new to the world of aquarium sumps. The sump comes in a range of sizes to suit tanks with different capacities from ten right through to 300 gallons, and you can choose a model with either a dual or single intake.

Eshopps sump is a very popular brand that sits within the mid-range price. The sump’s design means that it fits into your aquarium cabinet without taking up too much space, and it’s very straightforward to set up provided you have the relevant experience. That said, the installation instructions aren’t the easiest to follow, and you may find that you need to refer to users’ YouTube videos that explain the process more clearly.

Despite the product’s compact dimensions, the sump still has a large bio-ball capacity. The sump filter provides excellent biological filtration and comes with an overflow box, cover, and drip tray. You also get a filter pad and egg crate included with the sump kit. The product is made from high-quality acrylic, making the sump very durable, and it can be used for both freshwater and marine tanks.

What we like:

• Smart, easy to access the pump
• Includes a built-in refugium
• Overflow box
• Large bio-ball capacity

Room for improvement:

• Installation instructions could be clearer for novice hobbyists

2. Esh Sump Reef System Rs-75

The Esh Sump Reef System is designed for those looking for a way of making the best of their marine aquarium without the usual intrusion of filtration equipment spoiling the look of the tank.

This aquarium fish tank sump is generally recommended for use with a marine reef system from a ten to 75 gallons capacity, although you could also use it for a tropical, freshwater fish tank.

The sump sits underneath the main display tank and works as a filter, as well as a holding area for calcium reactors, protein skimmers, heaters, and more. The compact unit will fit inside aquarium cabinets that measure 18″x10″x16″ inches or greater.

The sump is made from thick, high-quality, super-clear glass, includes a refugium area, and will also accommodate a small return pump and sterilizer unit. This is the third generation edition of the sump, which has been upgraded to run incredibly quietly. Users report that the system is very efficient and is also easy to access for cleaning once it’s set up.

What we like:

• Reasonable price
• A very compact unit that will fit most cabinets
• Excellent quality and well-made

Room for improvement:

• The input from the tank is the largest part of the sump, and the output is one of the smallest

3. Aquarium Masters 200 Gallon Reef Sump

The Aquarium masters 200 Gallon Reef Sump is designed for use with marine, saltwater, and coral frag aquariums with a capacity of up to 200-gallons.

This sum is extremely well-made and has quality cell-cast acrylic panels with flame-polished edges, making this sump extremely durable and longlasting.

The sump’s compact size means that it won’t take up too much space in your cabinet. You do get instructions with the sump that is relatively easy to follow, making the equipment easy to install and use.

What we like:

• Compact, space-saving size
• Easy to install and use
• Reasonable price

Room for improvement:

• Can only be used with a saltwater aquarium
• Only suitable for use with medium-sized tanks up to 200 gallons

4. CPR AquaFuge2 Hang-On Refugium

Refugiums are specifically designed to hold the living organisms of the aquarium. However, you can still add other equipment, such as pumps and filters, if you need the extra space.

The CPR refugium is very reasonably priced, and it’s also extremely easy to set up. Simply hang the refugium on the back of your tank, connect up the pipes as per the manufacturer’s instructions, and you’re good to go! With the refugium, you also get a small AquaFuge 2 Powerhead that can process up to 2.5 gallons of water, together with a medium and large variation which can process 3.6 and 4.7 gallons, respectively.

The main downside to this product is that it is a lot smaller than a regular sump, which makes it only suitable for use with smaller tanks and caring for a few select organisms. You’ll also need to organize your own lighting design if you want to keep creatures in the refugium.

What we like:

• Affordable price
• Comes with three pumps
• Includes instructions and all the pipework required

Room for improvement:

• You will need to buy a lighting system if you want to keep organisms in the tank

5. Eshopps AEO15005 Refugium

The Eshopps Refugium is an excellent refugium that is designed to be a stylish and sleek solution for aquarium owners who want to maintain the aesthetics of their display tank.

This product is a miniature ecosystem that can be used for storing all your tank equipment, housing sensitive plants or creatures, or simply to increase the water volume of your aquarium. Uniquely, this sump is made of acrylic and foam. That makes the equipment extremely lightweight and portable while ensuring that the kit is strong and sturdy too.

The filter and stoppages are built-in, and the operation is very quiet, so you won’t be disturbed while watching TV or working. The refugium is suitable for tanks up to 100 gallons capacity and has plenty of space for additional pieces of equipment. The compatible micron bags are readily available online too.

What we like:

• Reliable and high-quality sump that performs very well
• Can be used for tanks up to 100 gallons capacity
• Micron bags readily available
• Spacious enough to fit additional tank equipment

Room for improvement:

• Accessing the return pump can be tricky once the sump is installed

What is an aquarium sump?

An aquarium sump is a tank that sits underneath your main tank, containing your protein skimmer, filter, heater, and any other equipment that you use to maintain your fish tank.

So why keep all your kit in an aquarium sump?

Advantages of an aquarium sump

There are several advantages to an aquarium sump:

• Keeping all your kit in your display tank can be an eyesore. So, storing everything in a sump underneath the tank keeps it out of the way and out of sight.
• Having all your equipment in a sump means that you have easy access to it. You won’t disturb any of the creatures in your aquarium when carrying out routine maintenance jobs or if you need to replace it.
• A sump aquarium enables you to expand the water volume of the tank. That gives your water more stability and also provides more capacity for fish, corals, and invertebrates. For example, a sump tank allows you to increase the capacity of a 55-gallon tank to 71 gallons, which is a pretty notable amount.

How do sumps work?

All sumps are designed to work in basically the same way:

1. Water flows into the sump from the main display tank above.
2. After entering the sump, the water flows through a filter sock that extracts any large particles or debris.
3. The water then passes through the area of the sump that contains the protein skimmer (in a marine tank setup). Here, the water is skimmed with foam fractionation to get rid of any organics.
4. Then the water moves through into the refugium area where it is biologically purified.
5. The final stage involves passing the water through baffles, which trap any microbubbles.
6. The return pump then moves the water back into the display tank, and the process is complete.

Now, here’s a breakdown of how the individual components of the sump magazine work.

Filter sock

The filter sock is the first step to catching and removing any particles of dirt and debris from the water. Water flows out of the display tank and through the filter sock. Any debris that’s suspended in the water is trapped in the sock, leaving the water clean.

Filter socks are made from fabric or mesh and are roughly the same shape as a tube sock. The filter sock fits over the water pipe that drains from the display tank into the sump. Not all sumps incorporate a filter sock, having parts called refugiums instead.

Protein skimmer

If you have a reef tank, you’ll need a protein skimmer. That’s a device that cleans the water by using bubbles to scrub all kinds of harmful substances from the water. Generally, the protein skimmer is situated upstream of the refugium, as putting the protein skimmer after the refugium may skim out any beneficial invertebrates that the refugium is producing.

Refugiums

The refugium is a naturalized element of the sump where organisms living in the sum remove impurities from the water, rather like a biological filter.

Marine hobbyists often use the refugium to keep a deep sand bed. A deep sand bed consists of live sand that harbors both anaerobic and aerobic bacteria. The bacteria process waste products, converting harmful ammonia into nitrites and nitrites to nitrates, which are then removed from the system. A sump refugium also contains a macroalga, such as cheatomorpha or other minute invertebrates.

Some hobbyists also add live rock to the refugium area to provide extra filtration and a substrate for the bacteria and invertebrates to grow. As the sump is below the main tank and well away from predators, you may find that tiny beneficial copepods live and reproduce there, creating a natural, nutritious live food supply for fish and corals.

Baffles

Baffles are narrow dividers that force water to flow over and underneath to trap bubbles.

The water flow forces bubbles underneath the first baffle. The bubbles are then trapped on top of the second baffle, and so on until bubble-free water flows underneath the final baffle.

Return pump

A return pump then pushes the water up and back into the aquarium.

Water top-up systems

If you have a marine tank, water top-up systems are crucial. Many marine tank maintenance equipment items must be housed in a certain water level for them to perform efficiently. If you have a water top-up system in your sump, that could save you lots of time and hassle in keeping the water balance constant.

Such a control system will help to replace water that is lost through evaporation. When water evaporates from a marine tank, salt is left behind, upsetting the balance of the water chemistry. An auto top-up system has a sensor that can detect the water level in the sump’s return chamber. When the sensor detects a drop in the water level, it automatically supplements the loss with the water from the top-up tank. That keeps the salinity stable so that you don’t need to top-up the water manually every day.

Benefits of a marine fish tank sump

A fish tank sump increases the total volume of water in your tank, which in turn means improved water stability. Also, water temperature won’t fluctuate as easily in a larger amount of water, meaning that any alterations to water chemistry take place more slowly.

Open systems in the aquarium can allow water to leak out. For example, trickle filters and protein skimmers are both open systems. These are designed with openings that enable waste, air, and water to escape. Thanks to that design, you’ll need something in place to catch any overflow water that passes through, and that’s where a sump tank comes in. Overflow water trickles down into the sump. The water is then pumped back into the tank, and the process is repeated.

A sump tank enables more efficient surface skimming of a marine tank. The proteins that accumulate on the water surface appear oily and can cause issues with light penetration, which is essential for the health of corals, and the nitrogen/oxygen exchange between water and air can also be affected. An aquarium overflow box allows for constant skimming of the water surface through the addition of water from a sump into the tank. The water then overflows into the box, which then passes through the remainder of the filters.

How to choose an aquarium sump

There are a few things that you need to consider when choosing an aquarium sump:

Flow rate

Probably the most important thing to look at when you are choosing a sump for your aquarium is the flow rate. That’s essential if you want to keep your water absolutely pristine.

Basically, the aquarium sump’s flow rate should equate to at least six times per hour times the size of the tank. For example, if you have a 10-gallon tank, the wet-dry filter rate should be at least 60 gallons per hour.

Size

The absolute minimum water capacity of a sump system should be at least 20% the size of the tank. That said, the bigger the sump is, the better.

Intake pipes

Most fish tank sumps come with a dual intake design, although you may come across exceptions to that. The idea of the dual configuration design is that it accelerates the filtration process because the secondary pipe takes on some of the load. Also, a dual intake helps if the primary system becomes clogged, as the secondary pipe then comes into play.

In summary

An aquarium sump is designed to improve the efficiency of your tank’s filter and water quality control systems, as well as to improve the aesthetics of the tank. You can use a sump for both freshwater and saltwater aquariums, although such systems do have many benefits for reef and marine aquariums.

Although it is possible to build your own sump, it’s recommended that you buy one. Experienced hobbyists may decide to customize a shop-bought sump, although a commercially manufactured sump, such as those we’ve featured in this guide are usually the best option.

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