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Waterfall Spillway vs a Fountain

A waterfall spillway vs a fountain nozzle compared: aeration, noise, koi preference, evaporation and which suits a koi pond.

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The short version

Both aerate by disturbing the surface. A waterfall spills a broad sheet, aerates well, sounds pleasant and suits koi, which dislike heavy surface turbulence overhead. A fountain throws water into the air, aerates efficiently and increases evaporation and drift in wind. Choose the waterfall for a koi pond; choose a fountain for a formal water feature.

Best for koi ponds

Waterfall Spillway, 8 in Weir

~$70

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Best pure aeration

Blue Diamond ETA 80 Linear Air Pump

~$180

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At a glance

Waterfall Spillway, 8 in WeirBlue Diamond ETA 80 Linear Air Pump
Aeration Good Very good
Suits koi Yes Yes, and quieter
Evaporation Moderate Low
Noise Pleasant water sound Quiet hum
Works in winter Depends on freezing Yes, at reduced output
Running cost Pump dependent Low

Choose the Waterfall Spillway, 8 in Weir if…

You want the pond to sound like a pond and to aerate at the same time. A spillway returns filtered water in a broad sheet, which agitates a large surface area rather than a single point, and koi are untroubled by it.

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Choose the Blue Diamond ETA 80 Linear Air Pump if…

Pure oxygen transfer per watt is what you need, particularly on hot nights. A diffuser fed by a linear pump aerates more efficiently than moving the whole water column with a pump, and it costs far less to run continuously.

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Related

Comparison based on published manufacturer specifications and the general consensus of owner reports. We have not tested these products side by side. Confirm current specifications and prices before buying. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.

Frequently Asked Questions

Is a waterfall enough aeration for koi?

Often in cooler weather, and frequently not on a hot night at full stocking. Oxygen is lowest just before dawn in warm weather, which is when losses happen, so many keepers run both.

Does a waterfall lose much water?

Evaporation increases with surface disturbance and exposure, and a large waterfall in dry weather can lose a noticeable amount. Expect to top up more often, and dechlorinate what you add.

Should the waterfall run in winter?

In freezing climates many people shut waterfalls down, because ice can divert water out of the pond and empty it overnight. Aeration at depth is the safer winter approach.

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