At some point during your research into aquariums, this thing called a ‘Sump’ may have kept popping up and I remember thinking ‘What the heck is that‘ when I first heard about them. My idea of a sump was something that sits under my house to stop the basement flooding! How did that have any connection to an aquarium?
An aquarium sump is an additional tank or vessel that is usually installed in the aquarium stand. Water moves from the aquarium to the sump and back. Sumps provide additional space for installing filtration equipment out of sight and increase water volume to help maintain water stability.
When selecting your next aquarium a sump can be a very beneficial addition to both a freshwater and saltwater tank so let’s go and look at the sump and discuss why you should really look at getting a tank with one!
Contents – Click To Jump To That Section
- What is an Aquarium Sump?
- How Do Sumps Work?
- Aquarium Sump Sections
- Types of Aquarium Sump Design
- Where to Install an Aquarium Sump?
- Flow Rate Through Sump
- Sump Installation Precautions
- Aquarium Sump Vs Canister Filter
What Is An Aquarium Sump?
In its most basic form, a sump is an additional tank, vessel, or container that sits outside of the aquarium. The sump can be a simple single chamber container or a purpose-built tank with multiple chambers that each have a specific purpose.
The main benefits to adding a sump to your aquarium are:
Increased water volume
Adding a 20g gallon sump to a 50gal aquarium has just increased the total water volume by 40%! This can really help keep water parameters more stable.
There is nothing worse than seeing a beautiful aquarium but then be distracted by cables, pipes, and gadgets hanging off every wall in the tank.
Filtration equipment comes in many sizes and when you are limited to what size filter you can physically fit in/on the aquarium, it can shrink the product selection you have to choose from. Having a sump allows you a greater choice of filtration equipment.
Having a sump allows you more space to add additional filter media to help control parameters like nitrates and phosphates. Chemical media can be placed into mesh bags or media reactors that can hang on the side of the sump.
Adding material to increase bacteria surface areas like MarinePure (Amazon.com) blocks can dramatically increase the biological load (bioload) the aquarium can now support = More livestock.
A sump allows you to install devices like Refugiums or Algae Turf Scrubbers to grow the algae out of sight rather than it growing all over your main aquarium.
To help you understand more about what a sump is you can find a great selection of varying sized sumps to reference while you read through this article Here at Aquarium Specialty.com
So as you can see a sump may not sound like much at first glance but the benefits far outweigh the cons and if you have not bought an aquarium yet or are thinking of an upgrade then an aquarium with a sump will be one of the best decisions you will make in this hobby!
How Do Aquarium Sumps Work?
Sumps work by having water drain down from the main aquarium via a weir and overflow section and into the sump. The water then passes through the filtration in the sump before being pumped back up to the main aquarium.
The circulation of water never stops providing the ‘Return Pump’ is operating. As the water gets pumped back into the main aquarium, it passes through a weir and drops into the overflow section. This is what keeps the water level in the main aquarium constant. It then drains into the sump and is then pumped back to the main aquarium.
Think of this just like the overflow hole you see in every bathroom sink. When the water gets too high in the sink, it goes through the hole and down the drain pipe.
This is exactly how the aquarium/sump system works. But instead of the water flowing out to the sewage treatment plant, it flows into a vessel under the sink, gets filtered, and pumped back out of the faucet.
If you would like to find out more about how to size and select the correct Return Pump for your sump please be sure to check out my article: Aquarium Return Pumps – Step By Step Selection Guide
What Are The Different Parts Of An Aquarium Sump?
Sumps can be as basic as a bare glass tank or can be custom machined from acrylic to do whatever the owner wishes but most sumps have some common sections within them to help improve the efficiency of how the sump works.
This first section is where the water enters the sump from the main aquarium. There can be just a single drain pipe or multiple drain pipes collect in this area if the aquarium has 2 or 3 overflow sections.
It can either be its own covered section to prevent water splashing everywhere and creating salt buildup, or it is usually combined with the next section – The Mechanical Filter Section.
Mechanical Filter Section
The first part of the filtration that the water meets in the sump is the mechanical filters. These can be socks made of filter material, sponge pads, mats made of filter floss, or a relatively new device that is taking the market by storm – The Fleece Roller or Roller Mats as they are known.
The main job of the mechanical filter is to catch the large particulate matter suspended in the water so it can be removed before it gets chance to break down and decay.
This section is more applicable to saltwater aquariums and is where the Protein Skimmer is placed. Once the large particles have been removed by the mechanical filter, the protein skimmer gets to remove the Dissolved Organic Compounds from the water.
Protein skimmers have a recommended water height that they must sit in and some sumps come with an adjustable wall on the Bubble Trap to allow the owner to set the water level height in the skimmer section.
For those sumps that are unable to set the water level height, most aquarists make feet or a shelf to sit the protein skimmer on so it sits at the optimum recommended height.
Bubbles are a big nemesis in saltwater aquariums. They are very popular in freshwater aquariums but we need to prevent them as much as possible in saltwater. As the water drains into the sump and goes through the protein skimmer it becomes full of tiny microscopic bubbles.
Microbubbles can distress fish and coral and because of the strong lighting in a saltwater aquarium, they really show up in the water column. Aquarists want their water to be as pristine & clear as possible and a bubble trap is a great way to help achieve this.
A bubble trap is a series of 3 baffles that trap bubbles and release them from the water. As the water cascades over the first baffle, its bubbles are released and travel upwards. The water then flows down and under the second baffle with virtually no bubbles in it. Any bubbles left are released as the water travels up and over the third baffle.
This simple device prevents any bubbles being sucked into the return pump and blown into the main aquarium.
This section is where the Return Pump is located. The job of the return pump is to send the water back up to the main aquarium so more water can pass into the overflow and return to the sump to pass through the filters.
Pumps can either be a submersible type and sit within the water of this section or be an external pump and draw the water from this section.
The important part every aquarist needs to know is that this is the section where the water level will decrease as the aquarium water evaporates. If left unnoticed the water would drop until the pump runs dry which will cause the pump to fail.
The other major problem with water evaporating is that it leaves the salt behind, so as more water evaporates the remaining water will become saltier as the ratio of water to salt reduces.
To overcome these two problems one of the first upgrades an aquarist will purchase is an Automatic Top Off System. You can find out all you need to know about ATO systems in my article: What Is An Aquarium Auto Top Off?
Additional Sump Sections
If you have space where the sump is going to sit or you wish to build your own custom DIY sump then there are two additional sections you can install to make the ultimate sump:
1. Refugium Section
A refugium is an area dedicated to growing macroalgae and allowing Copepods to grow without being eaten. By growing macroalgae in this area, you can dramatically reduce the amount of phosphate and nitrates in your aquarium allowing for cleaner and healthier water.
For a far more in-depth look at Refugiums please take a look at my article on them: What Is A Refugium?
2. ATO Reservoir
In the return section of the sump, I mentioned how this is where evaporation occurs, and to keep stable water parameters we can install an Automatic Top Off system to replenish the evaporation with freshwater.
This freshwater needs to come from somewhere and usually most people fill a 5-gallon pail with freshwater every week to keep the system working. Having a reservoir built into the sump keeps everything neat and tidy.
Are There Different Types of Aquarium Sump Design?
There are so many designs of sump available that you will have no problem finding one that fits your available area or can have all the sections you need. If you are unable to find one then you can build your own like I did or have one custom made.
These next designs will give you the basic layouts of the most common sumps available.
The Most Basic Sump Design
The mechanical filter, skimmer section & return sections are all together – No baffles or bubble trap.
This is the simplest option but provides no way of removing any bubbles or keeping the water level a constant height due to evaporation of the whole section.
The Most Popular Sump Design
Mechanical filter section and skimmer section in one area and a bubble trap with a return section.
This allows the skimmer section can have a constant water height and the return section can be bubble free.
3 simple glass or acrylic pieces are all that is required to improve on the Basic Sump Design
The Most Efficient Sump Design
Installing a sump with a built-in Refugium is a great choice for those who can fit it. By Tee-ing off the return pipe the owner can install a valve to set the flow rate through the Refugium to allow the mass of Macroalgae to turn.
The Refugium water then cascades over a dividing baffle and back into the return section.
The Ultimate Sump Design
This design of sump adds an area for a ATO reservoir. Having 5-10 gallons of freshwater available for the system means this area only has to be refilled once a week (depending on the tanks evaporation rate).
A solenoid valve on a timer or toilet-style float valve can allow for this section to automatically remain filled too!
The Compact Sump Design
For those owners that have a Cube-Shaped aquarium or are tight on space, having a compact sump allows for all the efficiency of the larger sumps but in a more compact space.
These require a little more careful equipment selection to be able to fit in the sections and maintenance can be a little tighter to work on, but overall a great type of sump!
Where Do You Install an Aquarium Sump?
This section is broken down into two parts:
- The overflow part of the aquarium/sump installation
- The physical location of the sump itself
The Aquarium Overflow
If you have a sump, you need a way to get the water from the display tank down to the sump. This is where a weir and an overflow come in.
The weir acts as a barrier to setting how high the water level is in the main aquarium. It usually contains teeth or grooves cut into an acrylic sheet to prevent snails, crabs, and fish getting into the overflow section.
The weir also acts as a surface skimmer to pull any junk or debris floating on the water surface into the overflow to be taken to the filtration.
The overflow section is where the water collects after cascading over the weir before entering the drainpipe to run into the sump.
I have seen and worked on many of the popular types and I’m going to guide you through each type:
Reef Ready – Drilled by Manufacturer
You can buy tanks pre-drilled from the manufacturer with a Drain Pipe, Return Pipe, and Overflow pre-installed. These are very good tanks and are very popular. Reasonably priced too.
Internal Overflow – Drilled by Owner/Store
This type of overflow is very popular with the DIY’er as it allows you to custom craft your tank to suit your home and set up. An internal overflow uses a box on the inside of the aquarium with a hole or holes drilled through the side pane to either a plumbing bulkhead (Durso Method) or another box with which several drain pipes can be fitted (Herbie & Bean-Animal Methods).
‘Ghost’ Internal Overflow
The Ghost Overflows are a great choice as they are very low profile with the minimum amount of box on the inside of the aquarium. They do disappear well into the back/side walls and will be my choice on my next aquarium. They come in various sizes and allow for multiple drain pipes making them silent in operation (Bean-Animal Method).
External Overflow – Custom Tanks
This type of overflow is also very popular especially if you are having your tank custom built. This overflow has the side/back pane notched out at the top to provide the exit for the water to fall into a collection box on the back of the aquarium.
A black acrylic panel is then placed over the pane with teeth machined into it to keep critters out of the overflow. The only part of this overflow you can see from the front is the teeth on the weir.
These are the best overflow in my opinion but cost the most because the glass panel has to be machined and a glass box constructed on the outside of the aquarium. You are able to fit any of the 3 drain styles into it (Durso, Herbie & Bean-Animal) making it super silent.
If you are having your aquarium custom built this is the overflow to pick!
I have left this overflow until last because, in my opinion, they can create so many headaches. They are for tanks that are not drilled. They provide a means of moving water out of the display tank and down to the sump by using a siphon.
They siphon water over the rim of the aquarium, collect it in a box and send it down the connected drain pipe.
I cannot advise you enough to stay away from these overflows. Just have your tank drilled or buy one drilled. They are easy to drill!
This type of overflow has caused me more problems on clients’ tanks because when you get a power outage, the siphon breaks, and sometimes the siphon starts on power-up, and sometimes it does not.
You can buy a small pump that sits on top to suck water into the siphon, but it’s just a bandaid.
Many a tank has been flooded because the power comes back on, the return pump starts, but the siphon does not. The return pump then empties the contents of the sump into the display tank and it overflows!
Save yourself the headache and get a drilled tank if you want a sump or an All-in-One Aquarium.
The Sump Location
There are 3 main locations that most aquarists install their sumps in their homes.
- Within the Aquarium Stand
- Below the Aquarium in the Basement
- Behind the Aquarium in a Separate Room
1. Sump Within the Aquarium Stand
This is by far the most popular location for many aquarists due to the ease of plumbing and it is easily hidden away once the stand doors are closed.
There are some very, very nice sump installations in this world, and I’m surprised at just how much equipment can get crammed into a stand.
This is a typical way to install a sump in your system.
The convenience of this location is great but it comes with a few drawbacks:
- Limited space to mount additional equipment
- Electrical and Saltwater are within very close proximity to one another
- Difficult to move equipment in and out for cleaning and maintenance
- You are on your knees leaning into the stand – Trust me it hurts after a while!
2. Sump Below the Aquarium in the Basement
This is a great option if your home and budget allow for it. It doesn’t cost that much more, but the benefits of having space and everything mounted at a nice working height makes a huge difference in doing maintenance.
This is my sump installation in my basement. I was fortunate enough to have access to the location directly under my aquarium to build my ‘Fish Area’. This allowed me great access and the room to expand and install a Quarantine Tank and a Frag Tank in the early years after initial installation.
The only downside to this was I had to have a large return pump that was expensive, to push the water back up the 13ft to the top of my Display Tank.
3. Sump Behind the Aquarium in a Separate Room
If your home and budget can accommodate this it is by far one of the best installation methods you can do for the ultimate reef tank setup!
By placing the sump in a room behind the aquarium you have a clean slate on how to design the layout, the space to add as much equipment as you like, and room to add equipment later as your skills and tank progress.
The other good part about this is you are not pumping water up high, so the head pressure is greatly reduced allowing you to use a lower wattage return pump.
From a maintenance point of view this method is by far the best if your partner will allow you to convert a room into your ‘Nerd Room’! Having access to a sink and being able to plumb in your water storage tanks is worth its weight in gold!
This may seem daunting but once you have spent some time on your knees under the stand you will be planning your ‘Fish Room’ for your next build!
What Is The Recommended Flow Rate Through An Aquarium Sump?
The main purpose of the sump as we described earlier is to house equipment and provide greater water volume. The two main pieces of equipment that are installed in most sumps are the Protein Skimmer and Heater/s. The idea is to find a return pump that matches the recommended flow rate of the protein skimmer.
The protein skimmer will have an optimum flow rate that it was designed for and most aquarists recommend anywhere from 3x – 5x your tank capacity through your sump every hour.
My aquarium is 75 gallons so 3x volume per hour would be 75×3=225 gallons/hour (GPH) flow rate.
My protein skimmer is designed to operate around 200GPH so here is where I began the search for which return pump to use.
My return pump gives around 800GPH at 12ft head height which is perfect for my setup because my sump is located in the basement below my aquarium. I have a manifold running additional equipment so I’m able to throttle down my return to the tank with a valve so that the flow through the sump is around the 200GPH rate.
Do not get confused with the sump flow rate and display tank flow rate. Your corals will need massive amounts of flow rate, but this is created using wavemakers or powerheads.
All your return pump is for, is to set the flow rate through your sump and return the water back to the display tank.
By having a slow flow rate through your sump, your water will get maximum contact time with the Protein Skimmer and your Heaters/Chiller and allow them to operate at their maximum efficiency.
Are There Any Aquarium Sump Installation Precautions?
The two main areas I have seen cause problems with new sump installations fall under one of the following categories. By being aware of these precautions to take you can dramatically increase the chances of a mishap occurring with a new sump:
- Flooding Prevention
- Electrical Safety
Read on to find out how to keep safe and prevent a huge mess!
Being an aquarium owner, one of the biggest fears many people have is flooding, especially with saltwater. If you have a flood with saltwater the damage can be huge! Not only does the water create problems but once it dries the salt is left behind making a big job, even bigger.
Making your aquarium and sump as flood-proof as possible is an absolute must, so here are some things to be aware of and steps to take to prevent a flood:
Once you have a sump installed into your system you have to make sure the operating water level in your sump is set up correctly.
During a power outage, the water that is in the pipe going up to the tank from the return pump is going to drain back down into the sump. If your display tank is considerably higher than the sump and you have a large diameter pipe, you could have a lot of water draining back down.
Many people use a Non-Return Valve on the return pump to prevent this, but if that fails and your sump level is not right, you will flood.
To set up your sumps operating water level I suggest this:
- Fill your sump to 50% full with the return pump running.
- Disconnect the power to the pump and let the water back drain into the sump.
- Measure how much the water level in your sump rises. This now shows you how much gap you need to leave at the top.
eg: Back Drain amount rose sump water level by 4″
- Set normal operating water level to 6-7″ below the top of your sump. ie: Water changes should refill back to this level and have your ATO set at this level.
- Draw a line on the sump glass at the normal operating water level. This allows for quick glances to see sump is at the correct level and your ATO is working properly.
Non-Return or Check Valves
If you have a strong desire to use a non-return valve that is OK. Just make sure you have your water level set correctly, or if you are unable to do the above step because too much Back Drain water comes in, you then have to use an NRV (Non-Return Valve) if you cannot fit a bigger sump.
When you are selecting an NRV I would suggest using the valves that have a flapper valve inside of them, rather than a spring-loaded valve.
The flapper valves take a lot less pressure to open compared to the spring-loaded valves and this will give you more flow out to your display tank. You don’t want to be spending money on a good return pump and have all its pressure taken away because of a valve.
The other tip I recommend is spending a little extra money and buy the see-through valves with the union connections on each end. This way you can see if they are working correctly and it also allows you to see when it needs cleaning.
You will see an arrow molded into the side of the NRV. Make sure this is Pointing Away from your return pump!
You can find these clear Check Valves HERE at Amazon.com
Next, install a ball valve between your NRV and Display tank, this way you can isolate the water in the pipe above and easily remove the valve for cleaning.
Cleaning is the key to Non-Return Valves!
Improperly Sealed Aquarium Overflow
I have seen a few floors flooded due to an improperly sealed overflow in the display tank. Once the water drains out of the overflow in a power outage, the water in the display tank should not leak or creep into the overflow.
Be sure to always leak check your aquarium AND overflow (outdoors) for several hours before you properly install your aquarium, to make sure it is all watertight where it needs to be.
Having a small leak into the overflow will continue to drain down into the sump. Even if you have set up your sumps water level correctly, a slow leak over 8-10 hours will overfill your sump and flood the floor.
Leak Check Before Installation Saves Flooding!
Clogged Filter Socks or Filter Floss
In the early weeks of your new aquarium be sure to keep an eye on how quickly your mechanical filter socks/floss begin to clog up with detritus.
Keep plenty of spare socks or floss on hand to replace your clogged ones regularly. Once this filter becomes clogged it makes it harder for the water to pass through it.
As your livestock increase, your filters may clog faster, so keep an eye on them.
Depending on the design of your sump you may not have a filter floss or sock water bypass in there to prevent a flood. I change my socks weekly, then have some filter floss in my bubble trap. I only place floss in 3/4 of the width of the bubble trap to allow water to by-pass if it becomes too clogged.
Ensure your filter socks are not near the edge of your sump, so if the sock/s do overflow, they dump the water into your sump and not out over the edge.
Sump Overflow Drain
If you can do this it may save your Butt! When you design your system you should always be looking at simple ways to cover your rear end. Having an overflow drain in your sump is one of them if your location allows.
In my sump, I drilled and installed a 1/2″ bulkhead about 1″ from the top of my sump, then piped this into my house drain. This saved me from a flood when I found out my aquarium overflow developed a pinhole leak and we had a power outage 2 years after installation.
This is going to be a tough job for many people who have their sump located in the stand, and there is no basement access below or some form of house drain nearby, but lower than the Overflow hole in the sump, but if you can, do it! It is worth it!
Think of the Sump Overflow as an overflow hole in a typical sink.
There are two types I want to include here:
- High Water Level Alarm
- Leak Detection/Flood Alarm
These are lifesavers! I have both fitted to my aquarium via my DIY built controller and these alarms have saved me.
As humans, we all make mistakes, forget to turn something back on, drink alcohol while doing maintenance etc and we forget!
You can buy or create your own simple devices that can alert you straight away to a leak or an impending leak, so you can take action to prevent any further mess.
Pretty much all the aquarium controllers available today have this function and you can also have them shut down pumps, send you texts etc to help prevent the chaos getting worse.
If you cannot afford a controller, you can purchase a simple flood detection alarm that sits next to your sump and notifies you that you have water where you shouldn’t.
This one HERE at Amazon.com works great by sounding an audible alarm and linking to an app on your smartphone to provide an alert if you are not home to hear it! Oh, and it’s cheap! Please get one at the very least. You will not regret it!
Electrical safety with aquariums is absolutely paramount, ESPECIALLY with saltwater!
The two main hazards we are looking at here are electrocution and fire and both of them need to be considered carefully on how to prevent both, ALL THE TIME.
If you have a faulty piece of equipment or an item falls into the sump while you are working in it, you are going to be in real trouble if you have not taken the following precautions. Saltwater especially, conducts electricity so well that you need to be careful and do the following steps:
- Ensure all equipment has drip loops in the cable
- If electrical sockets are close, cover them with external weatherproof covers
- Ensure any electrical equipment is securely fastened to the aquarium stand or similar
- Do not rest Refugium light fixtures on the top of the sump. Suspend them or use a fixing kit
- Beware of salt creep – Keep it cleaned off electrical items at all time
- Unplug any item while working on it
- Beware of water splashing on an electrical item
- Keep a close eye on ‘Glass Heaters’, they can crack and cause electrocution.
To further aid in protecting you, have your plug outlets replaced to GFCI receptacles. These are designed to monitor the items plugged into them and trip at the first sign of a fault.
If you cannot afford an electrician to replace your receptacles you can use a GFCI Adapter that you plug into the wall.
This GFCI Adapter from Amazon.com is perfect for helping to keep you safe. As with everything be sure to test the manual test function regularly.
Many people complain about GFCI breakers or receptacles tripping and causing a tank crash. If it is tripping there is a piece of equipment that is not working correctly and you need to further investigate.
Fire is the second major concern with electrical safety. As mentioned before, saltwater is very conductive to electricity and an improperly protected device could ignite when it fails and cause a fire.
Fire can start in an aquarium stand and spread to the surrounding items.
A good tip I got told a few years ago and I still use it to this day is to install a small smoke alarm inside the stand of your aquarium or the ceiling of your fish room.
Early detection is essential for the protection of not only your aquarium but also your home and family
If you wish to find out even more problems areas that can cause you stress with your aquarium installation I highly recommend you have a read of this article I wrote:
Aquarium Flood & Leak Prevention – 18 Problem Areas
Which Is Better – Aquarium Sump Or Canister Filter?
For many of you that have had an aquarium before you will be familiar with e the canister filter, but for those who are completely new to aquariums, a canister filter is a sealed canister that contains a pump that sucks water from your display tank, passes it through the various filter media to provide the cleaning and then returns the water back into the tank.
These type of filters are very popular in the freshwater aquarium hobby and they work well. They are relatively easy to maintain and are simple to set up.
I would recommend these for a freshwater tropical aquarium but not for a saltwater aquarium. I have found that they can be easily forgotten as they get tucked away and then owners procrastinate in cleaning them.
This leads to high Nitrate levels from the detritus (waste & debris) building in the filter media.
To find out more on Nitrate and the Nitrogen Cycle Click Here to read my article.
The other main problems with these are that you are limited to how much filter media they can hold and you still have to have some equipment in the display tank. Eg: Protein Skimmer, Heater, Chiller (If required) Supplemental Media Reactors, Refugiums etc.
These are a good filter, but in my opinion for a freshwater tropical aquarium only.
You can find out more about using canister filters from my article: Can You Use A Canister Filter For A Reef Aquarium?
Well, there you have it folks, pretty much everything I could think of that you would need to learn about installing a sump on your aquarium. Sumps are such a great addition and there is a reason when over 95% of saltwater aquarium owners use one and if you have a freshwater aquarium, it allows you to hide all of the equipment to allow the full beauty of the tank to be seen without distraction!
If you found this article helpful may I suggest a few more for you:
- Protein Skimmers: All you Need to Know!
- Selecting The Right Aquarium Return Pump
- What Is An Aquarium Chiller?
- How To Select An RO/DI System For Your Aquarium
- Aquarium UV Sterilizers – What Do They Really Do?