What is an Aquarium Sump and Do You Need One?

     The term aquarium sump might at first seem as a misspelling of "aquarium pump" to the novice aquarium enthusiast. In reality, an aquarium sump is an external water tank that is connected to the primary display tank via inflow and outflow water lines.

The primary functions of an aquarium sump are to increase the water capacity of your aquarium set up, to provide a centralized point from which to operate otherwise unsightly filtration equipment, and to have an easily accessible distribution point for water supplements, nutrients and other required additions to the water of your aquarium.

For the reasons stated above, aquarium sumps are most common in saltwater or reef aquariums, but can also be used in freshwater aquariums.

The increased water capacity is an obvious advantage regardless of your type of aquarium. Plainly stated, the greater the amount of water present in your aquarium setup, the greater the diffusion of potentially dangerous build ups of ammonia or nitrates. This extends the time in which danger thresholds for toxin build ups are reached, giving you a wider margin to work with in keeping your fish healthy. Increased water volume will also allow you to keep pH and temperature levels more stable.

Talking about increased water capacity will obviously prompt many to pose the question, "just how large is an aquarium sump?"

Generally speaking, an aquarium sump will be smaller than the display tank. Its water capacity should be 40%-50% of the primary tank. Its dimensions should be such that it may be placed in as close a proximity to the main display tank as possible, while preferably still being able to keep it hidden. This can be a disadvantage to some aquarium enthusiasts who may lack the sufficient space necessary to properly accommodate one.

Once setup, however, an aquarium sump will allow you to migrate your entire filtration system out of the display tank and into the sump. As the water from the main display tank is pumped into the sump tank, it can be run through sump filter socks, which are devices which mechanically filter debris down to the 100-200 micron level as the aquarium water enters the sump tank. These can be rinsed when debris begins to accumulate and are for the most part reusable. Protein skimmers can also be used in the sump tank to minimize foam and more importantly build ups of toxins. Before being returned to the display tank, the water can also be run through a chemical filtration agent, such as activated carbon or zeolite. One could even go to the extent of growing algae in the sump tank so as to lower water nitrate levels naturally before returning the water to the display tank.

Of course, having this centralized location where all of the water in your display tank gets circulated makes it the ideal location for adding any supplement that your display tank requires. In making such additions, just remember to take into account the total water capacity of your setup including the main tank as well as the sump tank. Do not make the mistake of only using your display tank's capacity in making your calculations for how much of a certain supplement to add.

As you can see, the advantages to having an aquarium sump (be it for saltwater, reef or freshwater aquariums) are those of improved filtration, greater water stability and improved aesthetics. Of course, in the case of freshwater aquariums or smaller saltwater aquariums, one has to measure the cost and added technical issues involved with setup and maintenance that a sump implies to the added convenience.

By in large, if you can accommodate an aquarium sump in terms of space, take some time to observe a few sumps in operation to get a hands-on feel for their technical operation. Then, if you are at the stage where your aquarium budget can afford it, proceed with acquiring one.