How Does an Aquarium Sump Pump Work?

An aquarium sump is a common feature in reef-style aquariums and can provide convenience and organization to a tank's equipment access. A sump is essentially a second, smaller aquarium or tank housed below the main tank, with both intake and return plumbing leading up to the main aquarium. A pump in the sump tank feeds water upward into the display tank and gravity is often used to take water back down to the sump box. A sump is often easy to set up and maintain and provides numerous benefits to your tank.

  1. Water Volume

    • A sump's additional water space increases the overall volume of water being filtered through the tank, making swings in pH or ammonia less likely. The added gallons also increase water quality by providing more gallons of water per fish housed in the display tank.

    Hidden Equipment

    • One of the primary purposes in having a sump tank is that the sump provides a hidden area to set up all of the tank's heaters, filtration and other equipment. Thermometers and protein skimmers are also commonly placed in the sump tank, which leaves almost no equipment visible in the main display aquarium. This is very desirable because it projects the appearance of a completely natural aquarium, free from clutter and wasted space.

    Increased Filtration

    • Sump pumps also work to allow increased filtration in the tank. Much more powerful filtering devices can be placed in the sump for aeration since there is no need to worry about too much water movement damaging delicate corals or other life. Additionally, added biological media can be unobtrusively housed in the sump for better biological filtration.

    Maintenance Access

    • The sump provides a perfect place to add top-off water, medications or other chemical additives. There is no need to worry about fish or corals receiving a concentrated blast of chemicals when they are added to the sump instead of the main tank, and the sump allows you to test water parameters and quality without disturbing tank livestock.

    Limitations

    • A sump obviously requires an additional amount of designated space below the aquarium. While it does act to eliminate clutter in the main tank, sometimes the added space requirements can be a hassle. Additionally, sumps can potentially overflow if the return pump fails, creating a constant siphon of aquarium water down and out of the main tank. Check valves are available to eliminate this problem, but must be installed and maintained properly.