Choosing the Ideal Aquarium Sump Size

Choosing the Ideal Aquarium Sump Size

Picking the proper sump size, brand, and design is critical to the success in your reef aquarium. Here are some important items to consider when purchasing a sump for your aquarium:

Let’s go through these one by one…

How big of a sump do I need for my size aquarium?

As a general rule of thumb, purchase the biggest sump reasonable for your space as having a large sump increases the overall water volume of your system, which in turn improves the overall stability of your tank. However, the common location for a sump is the stand. This also needs to house other equipment, so it is important to still leave plenty of space for any other equipment you need.

If you are fortunate enough to have a fish room, basement or other space to keep your sump and equipment, then it is usually possible to get a very large sump. As crazy as it sounds, it’s even reasonable to have a sump as large or larger than your display!

Will the sump fit inside my stand?

First and foremost, can you get the sump in the stand?  Many stands have supports located between the doors of the stand to improve strength and stability.  These supports however make the actual opening quite small, so it is important to check your measurements and make sure you purchase a sump that will fit into the opening.

On many stands, the supports can be temporarily removed during installation, however these supports should never be removed when the tank is full. On other stands, the opening in the back is larger than the opening in the font, however this likely means you will not be able to remove the sump without draining the tank and moving it away from the wall. If you want the ability to be able to remove your sump without draining your tank, consider purchasing a sump you can slip it in vertically and rotate down flat.

Regardless of how you decide to install the sump inside your stand, you will want to leak test your sump prior to installation seeing as once you have it installed and water flowing it becomes very difficult to remove.

Will the sump fit all the required wet items including skimmer, reactors, pumps and/or other equipment?

The 2 most critical items are the skimmer and the return pump. Most sumps have specific compartments / locations for each of these items and it is important to make sure you purchase a skimmer that will comfortably fit inside the skimmer compartment and a return pump that will comfortably fit inside the return pump compartment.

Simplicity Deluxe Reef Sump (Top-Down Angle)
Pictured above: Common layout of the compartments in a sump.

What water depth does my skimmer require?

Each manufacturer and model of skimmer will have a different recommended sump depth and it is very important that the water level in the sump matches that recommendation. Most sumps nowadays do provide some means of adjusting the water level within the skimmer compartment. If needed, it is also relatively simple to raise up the height of a skimmer using egg crate or other material.

Will the size of the sump leave enough room inside the stand for dry gear, like dosing containers, dosing pumps, controllers, power supplies and/or other equipment?

Most folks under-estimate the amount of equipment that is needed to run a successful reef tank and many pieces of equipment have multiple components. A return pump for example, has not only the pump body itself, but also an external power supply and a controller. The bottom line is that it all adds up quickly and you will want to make sure you leave enough room inside the stand for all the dry gear you would like to store inside.

Will the sump overflow when the power goes out?

The last thing you want to worry about during a power outage is whether or not you are going to overflow your sump and flood your floor. This is likely critical not only for your own well being, but also especially important to your spouse, significant other, roommates and if you rent your landlord.

During a power outage, water will automatically siphon from the tank down to the sump through the pipes used to return water from the sump to the tank and testing to ensure your sump can handle this water volume should be done regularly. And although a check valve may seem like a great option for preventing an overflow, it isn’t. There is a high likelihood of failure, especially after it gets a little dirty from operating. If you choose this option, test and test often.

In our opinion, a better solution is made up of the following 2 components:

  1. Use a sump large enough to accommodate all the water that will drain out of your tank during a power outage.  To calculate how many gallons of space you need in your sump, determine how far the water level will drop in the tank (in inches) during a power outage and then multiply this by the width and length of your aquarium and then divide by 231.  This will give you the total gallons you will hope stays in your sump, not on your living room floor.
  1. Drill a small hole right below the water line on each return line. This will allow air to be drawn in and stop the siphon once exposed thereby reducing the amount of water ending up in the sump. This can fail however, as algae and other debris can clog the hole, so don’t count on this as the only method to prevent floods.

To summarize:

  • Measure your system to determine if your sump will fit in your stand,will it be enough to accommodate the volume of water when the power goes out.
  • Prevent back siphon with holes drilled near the surface, or properly placed return lines.
  • Test to be sure you don’t spray water on the floor, overflow or run into other problems when your power is cycled off and on.

Dry floors make for happy people in your life! 🙂

Carefully planning your sump ahead of time will help to prevent any unnecessary issues that can be easily avoided.  Taking tank size, space, and equipment into consideration is crucial for a successful setup and prevention of overflows and space issues when adding new equipment.

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