Choosing the right return pump for your reef tank is one of the most important equipment decisions you’ll make. The return pump is the heart of your system, moving water from the sump back up to the display and helping drive filtration, gas exchange, and overall stability. In this guide, we’ll walk through how to size a return pump, what features to look for, and how to set it up for quiet, reliable operation.

How to Size a Return Pump for Your Reef Tank

A good starting point is to aim for a return flow of about 3–5 times your display tank volume per hour after head loss. High-flow needs are better handled by powerheads and wavemakers in the display, not by cranking up the return pump.

Step 1: Calculate Your Target Flow

For example, on a 75-gallon reef tank:

  • Target turnover: 3–5x per hour
  • 75 gallons × 3–5 = 225–375 GPH at the tank

Step 2: Account for Head Height and Plumbing

Head loss is the reduction in flow caused by pushing water upward and through fittings. To estimate:

  • Measure vertical distance from sump water level to display water level.
  • Add extra head for elbows, tees, and long horizontal runs (often 0.5–1 ft per major fitting).
  • Check the pump’s flow chart at your estimated total head.

If your 75-gallon tank needs 300 GPH at the display and you have ~5 ft of head, choose a pump that delivers around 300 GPH at 5 ft, not at 0 ft.

AC vs. DC Return Pumps: Which Is Best?

Modern reef systems frequently use DC return pumps, but AC pumps are still popular for their durability and simplicity. Each has pros and cons:

AC Return Pumps

  • Pros: Very reliable, simple, often cheaper, proven long-term track record.
  • Cons: Fixed speed, less control, often louder, can run warmer.

DC Return Pumps

  • Pros: Adjustable speed, usually quieter, soft-start, can integrate with controllers.
  • Cons: More electronics to fail, usually higher upfront cost.

If you value quiet operation, fine-tuning flow, and integration with a controller, a DC pump is usually the better choice. For a simple, budget-friendly setup where noise is less of a concern, an AC pump can still perform extremely well.

Installation Tips for a Quiet, Reliable Return Pump

Once you’ve chosen a pump, proper installation will keep it running smoothly and quietly.

Plumbing and Noise-Reduction Tips

  • Use flexible vinyl tubing on the pump outlet to reduce vibration transfer.
  • Place the pump on a silicone or rubber pad in the sump.
  • Avoid excessive 90° elbows; use 45° fittings or gentle curves when possible.
  • Match pump outlet size to plumbing size to avoid bottlenecks and noise.

For more on keeping your system quiet and stable, see our guide on reef tank plumbing basics.

Maintenance and Safety

  • Clean the pump every 2–3 months in a vinegar solution to remove calcium buildup.
  • Inspect the impeller for cracks or swollen magnets.
  • Keep a backup return pump on hand for emergencies.
  • Use a check valve only as a backup; always design your sump to handle drain-down during a power outage.

If you’re still designing your system, our sump setup for reef tanks article pairs well with this guide so you can plan pump size, baffles, and drain capacity together.

Putting It All Together

The best reef tank return pump is one that delivers the right flow at your actual head height, runs quietly, and is easy to maintain. Aim for 3–5x display volume through the sump, choose between AC or DC based on your budget and control needs, and install the pump with vibration and head loss in mind. With thoughtful selection and regular cleaning, your return pump will provide years of dependable service and help keep your reef stable, oxygenated, and thriving. For next steps, check out our beginner reef tank equipment checklist to round out the rest of your gear.

Sources

  • Sprung, J. & Delbeek, J. C. The Reef Aquarium, Vol. 1–3.
  • Paletta, M. The New Marine Aquarium.
  • Manufacturer technical sheets and flow charts from common aquarium pump brands.

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