How to add oxygen to your Koi pond

There are many ways

Nigel Caddock NI

What to use?

In the early 1990s this was an easy question to answer. Hi Blows air pumps were the only choice. Made in Japan imported by Hagen and simply unchallenged. Then the industry decided to turn air pumps into the number 1 discount loss leader in the business. All manner of cheapo repros emerged, good news on the surface as prices fell, but with the problem that in an effort to compete, manufacturers down specified components to the degree where reliability which was never previously an issue.

There are of course many ways of adding oxygen to your system. Waterfalls, watercourses, venturi, turbo air domes, and of course air pumps. Oxygen is transferred into water via intimate interfacial contact of air and water molecules.

As a rule of thumb the longer the contact time the better the O2 transfer. In general of all external constructions waterfalls are the most effective simply by virtue of the increased contact time they facilitate due to their nature. The downside to waterfalls and watercourses is that in addition to increased O2 transfer performance they also are effective at thermal transfer.

This is great in the summer when temperatures are high, but less good in autumn and spring when large air temperature variations can occur, and if you operate your waterfalls you could either get a big gas or electric bill for your heating or risk inducing large temperature fluctuations.

Best advice is make sure you build in waterfall/watercourse by pass units so you can return water either via the waterfall or an in pond return like a TPR (Tangential Pond Return). This additional operational flexibility is good design as well as offering a highly practical solution.

Chemical Stability

As an aside, one of the less understood benefits of high levels of DO is that toxic elements, notably ammonia, are less toxic when DO levels are elevated and vice versa. Consider a scenario - if for any reason you get an ammonia spike in the summer when temperatures are high and its a sultry day, its not hard to understand how we can end up in serious trouble in a relatively short period of time.

When your Koi are gasping at the surface consider again if the price of a spare/ supplementary air pump is really too high?