A sump is a supplementary tank that is placed under your marine fish tank and collects drainage and houses your equipment (i.e. protein skimmer, calcium reactor heater, etc.). Sumps are not essential for a marine tank, as some aquariums may come with a back filtration system or you may choose to use an external filter. However, if you are looking to create the best possible marine set up, a sump is recommended as you will be able to increase the water volume and house more equipment. 

Read more about sumps here on our blog.