Sump and Refugium Setup: The Complete Guide

Sumps: The Upgrade That Changes Everything

Running a reef tank without a sump is absolutely doable — plenty of gorgeous nano tanks prove that. But for larger systems, a sump adds more water volume, hides ugly equipment, provides space for a refugium, and makes maintenance easier.

What Is a Sump?

A secondary tank sat inside the cabinet below the display. Water overflows from the display into the sump, passes through various chambers, and gets pumped back up by a return pump. The extra water volume alone improves stability.

Basic Sump Layout

Drain/filter sock section — Water lands here first through a 100 or 200 micron filter sock
Skimmer section — Constant water level helps the skimmer run consistently
Refugium section (optional but recommended) — Macroalgae grows here under a dedicated light
Return pump section — Water level fluctuates with evaporation; ATO sensor usually goes here

The Refugium

A refugium section growing chaetomorpha (cheato) is a powerful addition:

Exports nutrients — Chaeto consumes nitrate and phosphate. Harvest regularly to physically remove nutrients
Pods habitat — Copepods and amphipods breed prolifically, providing live food for wrasses, mandarin dragonets, and corals
pH stability — Running the refugium light opposite to the display light helps stabilise pH swings

Setup: a small LED grow light, a tennis-ball-sized clump of chaeto, and enough flow through (not around) it. Harvest when it fills the section.

Return Pump Selection

Budget: Jebao DCP series (~£40–80)
Mid-range: Sicce Syncra or Eheim
Premium: EcoTech Vectra (~£200+)

Size for roughly 5–10x display volume per hour at the actual head height.

Practical Tip

Choose a sump with removable baffles or easy-clean design. Detritus builds up over time, and regular siphoning every few months keeps things running well.

Browse sumps from UK sellers — sumps are just glass boxes, so used ones are perfectly fine.

Running a sump or thinking about adding one? What setup works for you?