Powerhead vs. Wavemaker: Which Makes Better River Flow?

A river tank lives or dies on its flow. Hillstream loaches, White Clouds and vampire shrimp all need water moving past them. The question is what's pushing it. Most people choose between a powerhead and a wavemaker, and they make very different currents.

What a powerhead does

A powerhead is a small submersible pump that pushes water out of a nozzle in one direction. The flow is narrow, steady and strong right in front of it, then fades fast.

• Good for: pushing water down a long, narrow tank in one direction, blasting dead spots, and running a river manifold.
• Downsides: a tight jet can blow fish around and kick up sand. Older models run warm and take up space.
• Price: usually inexpensive.

What a wavemaker does

A wavemaker (also called a circulation pump or propeller pump) moves a much larger volume of water in a wide, gentle pattern. Many have a controller that can pulse the flow, ramp it up and down, or switch between pumps.

• Good for: moving the whole tank's water, varied flow that mimics a natural stream, and keeping debris suspended so the filter catches it.
• Downsides: costs more, and the pulsing "wave" modes are made for reef tanks. In a river tank you'll mostly use the steady or slowly varying modes.

Which one builds a better river?

For a true one-way "river" down the length of the tank, a powerhead feeding a manifold (a pipe with holes along one end) is hard to beat. It spreads the jet across the whole width of the tank and sends it all one direction. Our guide to building a river manifold shows how.

For a natural stream feel in a wider or taller tank, a wavemaker on a low, steady setting does a better job of moving the whole tank without making one blasting jet.

Many river tanks use both: a powerhead and manifold for the main current, and the filter return or a small wavemaker to keep the corners from going stagnant.

How much flow?

A common rule of thumb for a regular freshwater tank is turning the water over 5 to 10 times an hour. River tanks run higher, often 10 to 20 times the tank's volume per hour, counting the filter and pumps together. For a 55-gallon, that's roughly 550 to 1,100 gallons per hour.

Start lower than you think, and turn it up while watching the fish. If they're struggling to hold position and never rest, it's too much.

Placement tips

• Leave a calm zone. Rocks, roots and plants downstream of the pump give fish a place to rest. Even fish built for strong current need a break.
• Cover the intake with a sponge so shrimp and small fish don't get pulled in.
• Point the flow along the long side of the tank, not straight at the front glass.
• Watch the sand. If the current is scouring a bare patch, raise or turn the pump, or switch to heavier substrate.
• Keep surface movement. Rippling water exchanges more oxygen, which is part of why river fish do well in it.

A note on power outages

If the power goes out, both stop, and fast-flow fish feel the oxygen drop first. A battery air pump is cheap insurance. See our guide to keeping a tank alive in a power outage.

Sources (2)

Bulk Reef Supply: What Is the Difference Between a Powerhead and a Wavemaker? · Fish Tank World: Aquarium Circulation Pump Guide