Ice, oxygen and the cold weather


Not a Health & Safety warning about the dangers of eating butter but the amount of oxygen in the water today.

So why the interest in oxygen? Well, in advice about garden ponds I read on a web site:

‘Winter freezing is a problem for many small pond creatures. Holes should be opened in the ice to allow oxygen into the pond, and for toxic respiratory gases to escape.’

This is a common piece of advice. Is there any truth in it?

Well, there’s not much hard information to go on. But you can get a hint from today’s measurement of the amount of oxygen dissolved in my pond.

Today after pretty much continuous ice cover for the last five days there was 11.8 milligrammes of oxygen in each litre of water in the pond. This is close to as much oxygen as the water can physically hold: its 92% saturated at today’s water temperature of 4 C and there’s no sign of any decline as a result of ice cover.

So it looks like the ice hasn’t made much – if any – difference to the amount of oxygen in the water. In reality, a shortage of oxygen under ice is only likely to be a problem if you’ve got a lot of oxygen consuming fish. And even then, it will depend a lot on the size of pond and the amount of light getting through the ice to allow plants and algae to photosynthesise.


One Response to “Ice, oxygen and the cold weather”

  1. Should I break the ice on my pond? « The Garden Pond Blog Says:

    […] considerably higher than the last time I measured the oxygen concentration a few days ago – roughly […]

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