How much oxygen do I need in my pond?

unless your studying ponds in great detail its not worth buying one because it won't tell you anything you really need to know! Instead - check out what wildlife is living in the pond. It's a better guide to the pond's condition.

My dissolved oxygen meter: unless your studying ponds in great detail its not worth buying one because it won't tell you anything you really need to know! Instead - check out what wildlife is living in the pond. It's a better guide to the pond's condition.

Much is written about the oxygen levels in ponds and, although its been known for years that oxygen levels go up and down naturally in ponds, many people still worry about not having enough oxygen in their ponds.

I mentioned the other day that in my pond the water is about 90% saturated at the moment – enough for even the most sensitive of animals.

At least, it would be for a short time – put a big salmon in a small pond and it would soon be using up oxygen faster than the oxygen could be replenished. That’s why salmon don’t naturally live in ponds!

So how much is the right amount of oxygen?

The graph gives us a clue.

In May, dissolved oxygen concentrations in the early morning in my pond were a quarter to a third of what they were in the middle of the afternoon. I made these measurements over the course of a weekend. Did these big differences make any difference to the pond's wildlife? Probably not.

In May, dissolved oxygen concentrations in the early morning in my pond were a quarter to a third of what they were in the middle of the afternoon. I made these measurements over the course of a weekend. Did these big differences make any difference to the pond's wildlife? Not really.

My garden pond is pretty much like a wild natural pond: water more or less as clean as it could be, naturally colonised by plants and animals, and a good size and depth for wildlife.

In May there were big swings in the dissolved oxygen levels – because there were a lot of algae growing in the water. But there was nothing wrong with the pond. That’s what ponds are like.

Oxygen levels vary less in November - but the daily swing (low in the morning, higher after lunch) is still there

Oxygen levels vary less in November - but the daily swing (low in the morning, higher after lunch) is still there

Now, in November, the daily variation is damped down to just 3 or 4 degrees a day – but it still varies.

Fluctuating dissolved oxygen levels in ponds are essentially harmless. Unless you’re trying to keep sensitive fish in the pond, which wouldn’t naturally live in these conditions, they probably don’t do any harm.

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One Response to “How much oxygen do I need in my pond?”

  1. The ‘tadpole’ pond « The Garden Pond Blog Says:

    […] As we also saw last year you don’t need ‘oxygenating’ weed for tadpoles. Underwater plants do make oxygen, but they also use it, and algae will do exactly the same thing. A pond in full sun will be producing masses of oxygen without any plants (see the garden pond blog here to see how it goes up and down during the day). […]

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