By Sarah Goodwin‑Nguyen
Updated Mar 24, 2022

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A well‑designed sump is a versatile addition to any aquarium—freshwater, saltwater, or reef. By increasing the total water volume, it stabilizes pH, dilutes nitrites and nitrates, and expands the air–water interface for improved oxygenation. It also offers a discreet location for equipment such as protein skimmers, heaters, and chemical dosing stations, keeping the tank interior free of clutter and reducing the risk of accidental chemical burns to the inhabitants.

Step 1: Choose the Right Sump

Place the sump below the aquarium level. Regardless of the tank size, a larger sump provides greater buffering capacity and flexibility for future equipment additions.

Step 2: Drill Inflow and Outflow Ports

Drill two holes on opposite sides of the sump, positioned near the center to prevent overflow if the tank is turned off. The inflow port should be slightly higher than the outflow to maintain a gravity‑driven flow and avoid backwash. Cut the holes to the exact diameter of your PVC fittings.

Step 3: Connect the Sump to the System

Arrange the water path so that filtered water first enters the sump, then passes through the protein skimmer, UV or ozone sterilizer, and finally to the chiller or back into the main tank. This sequence maximizes filtration efficiency.

Step 4: Install the Powerhead

Mount a powerhead on the sump to push water upward through the PVC pipe to the sterilizers, chillers, or directly back into the aquarium. Use silicone sealant and a series of gradually larger PVC sections to create a “staircase” profile rather than a straight vertical run, ensuring steady upward flow.

Step 5: Seal and Test

Apply silicone sealant around all PVC connections and the drilled ports to make the sump watertight. Run the system at full speed to check for leaks, proper flow, and back‑pressure before fully integrating the sump into the aquarium.

Materials Needed

• Clean plastic, acrylic, or glass sump
• Electric drill
• PVC piping and fittings
• Silicone sealant
• Powerhead (sized for your system’s flow rate)

TL;DR (Too Long; Didn’t Read)

Use a gravity‑driven overflow method—PVC pipe from filter to sump—to efficiently move water. The pipe size depends on your filter’s flow; faster flow requires a larger diameter to avoid back‑pressure. A sump can house heaters, certain skimmers, and even live rock for natural filtration.