The Sump

for the week of 8/5/99

Many aquarium hobbyists (especially reef keepers) have begun to appreciate the value of a sump in their aquarium systems.

What’s a “sump”? – A sump is simply some sort of water-holding container that is usually placed below the display aquarium. Water from the display is drained into the sump and pump back up.

What are the uses? – Sumps can be simply a place to hold extra water, extending the capacity of the system without increasing the size of the display tank. If they are properly set up, they also keep the water level constant in the main tank even as water is lost by evaporation. They can be used to hold biological filter media (wet/dry or trickle filters are just glorified sumps) or growing plants (as in refugia and mangrove tanks) or other organisms that purify the water. Several or even many tanks can use a single sump, and share filtration, heat, UV sterilizers and so on.

What should a sump be made of? – Any durable, non-toxic watertight container can be used. Aquariums work just fine, although they generally do not allow easy access, since they are equally high all the way around. Commercial sumps, such as wet/dry filters, generally have a lower wall on one end for this purpose.

How big should a sump be? – Generally the bigger the better, providing it fits and is serviceable in the space available. It absolutely must be big enough to hold all the water that will drain into it if the pump is shut off.

Is there more? – You bet. Next we’ll take a look at how to get water from the tank to the sump and back again.

“Tip of the week” appeared regularly in 1999 and 2000.