Saltwater Aquarium Sump & Refugium Guide
If you've spent any time around reef tanks, you've probably heard people swear by their sump. At Tropical Treasures in Cheyenne, we tell beginners that a well-set-up sump and refugium is one of the biggest quality-of-life upgrades you can give a saltwater tank — and your fish. This guide breaks down what they do and how to get started.
What is a sump, anyway? 💧
A sump is a second tank, usually hidden in the stand below your display, that holds extra water and equipment. It hides your heater, skimmer, and return pump out of sight, adds water volume for stability, and gives you a place to dose and top off without cluttering the main tank.
What a refugium adds 🌿
A refugium is a section of the sump where you grow macroalgae like chaeto under a small light. As the algae grows, it pulls nitrate and phosphate out of your water naturally, which means cleaner water and less algae in your display tank. It also becomes a safe nursery for copepods and amphipods — free live food that fish like mandarin dragonets depend on.
Basic sump zones 🔧
Most sumps are divided into three sections by baffles: an intake area where water from the display drains in (often with a filter sock or skimmer), a middle refugium or media zone, and a return chamber that houses the return pump sending water back up to the display.
Getting your sump dialed in ⚙️
Match your return pump to your tank size and plumbing height, keep your sump water level consistent so an auto top-off can replace evaporation, and don't overfill the return chamber — leave room so a power outage doesn't flood your floor. Browse our equipment and supplies or call us at 307-369-1118 and we'll help you size everything for your setup.
Is a sump right for you? 🤔
If your tank has an overflow or you're drilling a new build, a sump is well worth it. If you have a small all-in-one nano without plumbing, you can still get many of the same benefits with a hang-on-back refugium instead.
The bottom line ✅
A sump and refugium add stability, hide your gear, and clean your water naturally — a combination that makes reefkeeping easier and your corals happier. Want help planning one? Stop by Tropical Treasures in Cheyenne or call 307-369-1118, and check out more tips on The Tank Buddy Blog.