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Saltwater Aquarium Guide Reef-keeping magazine
Tanks & Sumps

Reef Sump Design: Filtration, Refugium, and Equipment Layout

Three-chamber sump design from filter sock input to skimmer chamber to return, plus refugium integration.

By Saltwater Aquarium Guide Published

Skimz SC165 protein skimmer, an example of the in-sump skimmers used on reef aquariums
Photo: Skimz, CC BY-SA 4.0, via Wikimedia Commons (cropped)
In this article
  1. Chamber 1: Input + skimmer
  2. Chamber 2: Refugium
  3. Chamber 3: Return

A well-designed sump hides equipment, increases water volume, and adds a refugium for natural nutrient export. Here is the proven three-chamber layout.

Chamber 1: Input + skimmer

Filter sock or roller fleece catches detritus. Protein skimmer sits in this chamber at the manufacturer's specified water depth.

Chamber 2: Refugium

Chaeto algae under a 6500K refugium light consumes nitrate and phosphate while sheltering pod populations.

Chamber 3: Return

Return pump sits at the lowest point. Add an ATO sensor here so float-switch action does not affect skimmer water level.

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