Aquarium Sump Sizes

A sump is a reservoir containing water, which is typically placed below the main aquarium and is connected to it, via tubing or pipe. Sumps increase the overall volume of water in the system and thereby contribute to aquarium water stability. Filters and heaters are normally placed in the sump, thereby removing them sight. Aquarists also design sumps to function as specialized filters in their own right, such as a trickle or algal filter. Sumps can also contain a refugium, in which microscopic organisms are cultured as a food source for the fish in the main aquarium.

  1. General Size Considerations

    • In general, the sump should be as large as possible, but certain size constraints need to be applied. If the sump is to be housed in the aquarium cabinet, it cannot be larger than the available space within that area. Sumps increase the overall water volume of a system and larger water volumes require larger heaters and filters, which impact cost. Although it is not necessary for a sump to be too large, it must be large enough to handle the overflow water from the main aquarium, whenever necessary

    Power Outage Problems

    • The overflow on an aquarium channels water down to the sump, from where it is returned to the main tank, after being filtered. This sump pump will immediately stop working at the onset of a power outage. A sump must therefore be large enough to accommodate the volume of water that flows into it.

    Additional External Filter

    • As a rule of thumb, 1-gallon of bio-balls will filter 30-gallons of fresh water, or 20-gallons of saltwater. If the sump is being used primarily as a biological filter, these values will allow an aquarist to determine the minimum size of their sump. Space in the sump for mechanical filter material, in the form of filter floss and chemical filter material, which will normally be activated carbon, will also need to be factored in. Space for the overflow water from the main aquarium during a power outage, must be included as well. The hobbyist should therefore choose a sump which will house between eight and ten-gallons, even if they aim to use it only as an additional external filter.

    Specialized Filters

    • Sumps, which are used as trickle filters or refugiums, need to be large enough to perform these functions optimally. Refugiums typically contain mud or some other fine substrate in and on which minute creatures, such as copepods are propagated. Higher algae species, which remove excess nutrients from the overall system's water, may also be grown. Sumps which are almost the length of the main aquarium are required, if the aquarist wants to house filters, such as protein skimmers, in the sump as well.