Basic Sump

Intermediate Sump

Advanced Sump

Basic Sump Intermediate Sump Advanced Sump


A sump is a separate container of water that is connected to your display aquarium. It is used to house your filtration equipment out of plain sight and increase the total water volume of your aquarium system. The complexity of a sump seems to grow with tank size and experience. While sumps can be somewhat personal, with each one being unique to the tank it supports, there are basic components that all sumps share in common.

Read the article: What Is A Sump to learn more about how a sump can benefit your aquarium.

These plumbing diagrams will show you not only how simple or how complex a sump can be, but also help you to identify the fundamental equipment and components of a sump system.

Ready to buy a sump? Consider these helpful tips.

Basic Sump

This diagram shows the most basic bare-bones sump. A single drain and return water line with three chambers allows hobbyists to achieve basic mechanical and chemical filtration. The Crystal Series sumps from Trigger Systems are a great example.

Basic Sump

Your tank will have either an internal or external overflow box that always allows for a leak-free connection to your sump via the bulkheads. Water drains out of your display tank, through the overflow box, into the drainpipe, and finally down into your sump via the drainpipe. Rigid PVC pipe or soft vinyl tubing is most commonly used for aquarium plumbing connections.

The raw unfiltered water from your display tank first encounters filter socks which remove undissolved waste and other particulates from your aquarium water. It then moves into the next chamber where a Protein skimmer helps aerate your aquarium water and also pulls out dissolved and undissolved waste. This chamber is often one of the largest in your sump and is a great place to house a heater that will automatically maintain stable water temperatures.

The next auxiliary chamber can be used to house a wide variety of additional filtration equipment, filter media, or used as a refugium space. Some of the smaller sumps do not have this 4th auxiliary chamber which is completely optional and not absolutely required.

The baffles throughout the sump are simply the dividers in your sump and help direct water from one chamber to the next and maintain a constant water level where it is needed. A special series of baffles called a "bubble trap" is always built just before the return pump chamber. A bubble trap is designed to stop bubbles from entering your return pump which will create micro-bubbles in your display. 

The final chamber always holds your return pump which is the heart of your tank, delivering water from the sump back into the display aquarium via the return pipe. 

Every tank needs a power center or surge protector mounted within a reasonable distance of the sump for plugging in the equipment. Mount it up high, away from moisture and splashing, and always use drip loops when plugging in power cords.

Intermediate Sump

Intermediate Sump

In addition to all of the same components of a basic sump, intermediate sumps simply have more filtration equipment and automation devices, primarily helping to keep the environment more stable. 

Biological filter media provides additional surface area for bacteria and a filter media reactor makes better use of carbon and GFO. 

Notice the return water line splits off and feeds both the media reactor and chiller. This is called a manifold and will save you the hassle of using multiple pumps to run additional equipment. Gate valves are used to control the rate of flow into this equipment and can also control the amount of flow going back into your display tank. 

An ATO - Automatic Top-Off System is used to replenish freshwater that is lost during evaporation. The Freshwater Reservoir simply holds the necessary RO/DI water the ATO pumps into your tank when its sensors are triggered by a low water level. ATO sensors are ALWAYS going to be placed in your return pump chamber because this is the only chamber that actually changes water level as water evaporates because of the special baffling inside a sump. 

Advanced Sump

Advanced Sump

As your tank matures and you learn more about the hobby, there is certainly a wide range of gear you might find useful for your tank.  We highlighted three of the most common upgrades for advanced aquarists here but the customization doesn't stop here. A sump can be as complicated or as simple as you want it to be.  

A refugium is pictured in the auxiliary space this time. Most refugiums will contain sand and/or refugium mud for substrate, small chunks of rubble rock, and macroalgae. A refugium light is required to support the growth of the macroalgae, as the macroalgae grows it will absorb nitrate and phosphate, helping to control nutrient levels in your tank. The refugium also provides a safe haven for beneficial microorganisms such as copepods to grow and reproduce.

A calcium reactor is the most automated solution for calcium and alkalinity supplementation in a reef tank. They work great and once tuned, will provide the tank with very stable parameters without much maintenance.  That being said, they can be phosphate factories and suppress pH in the aquarium.

The good news, aquarists can also use additives and dosing pumps as an alternative solution for water chemistry supplementation. While calcium reactors are quite handy, dosing pumps are more and more common on reef tanks these days allowing the user to automatically deliver any kind of liquid supplements into the aquarium based on programmed schedules. While it does require more effort to use a dosing pump and the user must replenish additives, the initial investment of a dosing pump is more affordable compared to a calcium reactor.

If you could walk away learning one thing from this article, consider this.  An aquarium controller is the single most valuable device or investment you will make for your reef tank.  Controllers are essentially little computers that allow you to monitor and control conditions inside your tank. All of your lighting, pumps, and filtration equipment is connected which will ultimately make your life much easier and help protect your tank from failure.  Monitoring probes give you real-time measurements of things like temperature, pH, and salinity, then those measurements can be used to trigger actions using your equipment or send you a notification directly via SMS or email. This is just the tip of the iceberg in terms of capability too.

Watch Video: It’s BRS Recommended - The Neptune Apex Aquarium Controller to learn more about our favorite aquarium controller and decide for yourself if you want the most advanced protection for your tank. 

Choosing The Right Sump

Top Aquarium Sump Mistakes You Don't Want To Make! But Do You Even Need One?

When it comes to choosing a sump, your going to be faced with a wide variety of options and brands. You can even make your own sump using an old aquarium! As long as you follow these guidelines, you should walk away with a perfectly usable sump that will provide a great platform for your tank's filtration.

  • The sump should be no less than 25% of your tank's total water volume, the bigger the better.
  • The sump needs to fit inside your tank stand or proposed sump location, check overall dimensions.
  • Don't fill the display tank with water until you are ready because you might have to move things around to install the sump.
  • The sump needs to be able to hold ALL of the water that back siphons from your display. Test this after plumbing!
  • Our water volume calculator can be used to calculate sump water volume, just like a tank. Remember, most sumps only run about 50-60% full of water when in operation.

One major point to consider when deciding on a sump. The bigger the better is common advice from more experienced hobbyists and we say this for a few reasons. A larger sump means more water volume, more water volume equals stability. Larger volumes of water will not change as abruptly as smaller water volumes. Exactly why "nano reef tanks" can be difficult to maintain for those not willing to put forth the effort.

"More Room For Activities!" - Jokes aside, a larger sump gives you more room to install equipment and perform maintenance. Of course, the sump has to fit within the space you have and most hobbyists just put the sump directly under the display tank. The reality is, the sump doesn't have to go inside the tank stand. It can be set next to the tank, in your basement, or behind a wall in a "fish room". While remote sumps like this will require more complicated plumbing, they do have some great advantages.

Sump Flow Rate - How Big Should My Return Pump Be?

In modern aquaria, your sump flow-through rate should be no more than 3-5 times your total tank water volume per hour. This means your pump will circulate the entire volume of water in your aquarium 3-5 times every hour.

For example, say we have a 75-gallon reef tank. The flow rate should be 225 - 375 GPH.

This might seem slow, but the reality is you want that dwell time in the sump. This gives your aquarium water more contact time with your filtration equipment. In days past, we used to recommend anywhere from 5 to 10 times total tank water volume per hour but those kinds of flow rates really are just not required to achieve maximum filtration. Slower flow also runs quieter, results in less evaporation, and allows you to use a much smaller pump.

When shopping for return pumps, you need to get something that fits into your particular sump's return chamber so always double-check pump dimensions before making your final decision; you may have to physically measure the return chamber on your sump to ensure the chosen pump fits.

Flow Chart

When it comes to flow rate, choose a pump that can deliver the flow rates your tank/sump needs. Keep in mind your return water plumbing will apply some "head pressure" to the pump which slows down the flow. You can reference a flow chart (see above for Reef Octopus VarioS 8) to see exactly how the pump performs under various amounts of head pressure. Your pump will have its own flow chart and we try to include this information in the product description on our website or just contact our Customer Service team for help.

How To Calculate Head Pressure For An Aquarium Return Pump

  • Every 12" of Vertical Climb = 1 ft of head pressure
  • Every 90° elbow = 1 ft of head pressure
  • Every 10ft of horizontal distance = 1ft of head pressure

This will give you a pretty good estimate of how much "head pressure" your particular plumbing will apply to the pump. Always slightly oversize your return pump too because you can easily slow it down, but you can't make it go faster.

Modern-day DC water pumps give the user electronic control and classic AC water pumps can be throttled back with a ball or gate valve. It's a good idea to always plumb a control valve into your return water line for this very reason, it allows you to fine-tune the return flow rate. Not only for the sake of falling within the flow range that your particular tank requires but also to help equalize that return flow rate with the drain. Your particular overflow box and drain will operate best within a given range that is appropriate for your tank size, therefore, you want to be able to hit that given flow range with your return pump.