What is a Sump?

A sump based system is a system that utilizes two tanks. Typically one tank sits above the other. The top tank is the show tank and the bottom is the sump tank. The top tank drains into the bottom tank, and then the water is pumped back into the show tank. A sump based system has many benefits, here are a few.

Equipment
Maintaining a healthy saltwater aquarium requires that you keep the water quality high, consistent, and within certain parameters. In order to maintain those parameters additional equipment will be needed. The list of equipment that can be added to your aquarium is long. Most of it is designed to be functional, and therefore not pleasing to the eye. This extra, but often necessary, equipment clutter can be hidden from view in the sump.

*Another point to consider when purchasing and placing your equipment is heat. The larger the piece of equipment, the more heat it will likely produce. As with everything else in life, good design and high quality materials usually separate a quality piece of equipment from a cheap one. So it is possible to have a larger piece of equipment actually release less heat than a smaller piece of equipment.

Dilution
Fish produce a lot of waste. The more water you have in the system, the more dilute the waste. Less waste equals a happy tank.

Circulation
A saltwater tank needs a lot of water circulation. The goal is to circulate 10x-20x the water volume of the tank in an hour. If you have a sump, this greatly increases the capacity to do this. Along with circulation I will include aeration, or the absorption of oxygen into the water. Salt water does not absorb oxygen as well as fresh water. The simple act of the water overflowing the top tank on its way to the sump increases the amount of water that is in contact with air, helping to increase the aeration in the tank.

Maintenance
When you have to add water, chemicals, etc. to the tank, you don't want to have to pour it over your corals if you have any. Coral are sensitive, sessile creatures. They grow where they are planted (but they are not plants, they are animals). If you can add your water, chemicals, etc. to a sump, it will dilute out easier and be less obtrusive to the animals in your system.

I will discuss the draw backs to a sump based system in the next post.