Do leaves use up oxygen in garden ponds?

I like leaves in my pond

I like leaves in my pond

Many guides tell people to remove leaves from their ponds. Here’s a typical piece of advice:

‘When leaves fall in the autumn, try to keep them out of the pool if you can and rake out those that do get in.’

And a typical reason for doing it:

If vegetation falls into the pond water and decays the process of decay uses the oxygen in the water and releases carbon dioxide. This means that if large quantities of vegetation enter your pond then enough oxygen can be removed to cause the pond’s wildlife to suffocate.

Is any of this right?

I can only go from my own experience. In our garden the pond is now going through its second autumn: as you can see, there are quite a lot of trees and shrubs nearby, and they drop leaves into the pond.

Despite this, there is no shortage of oxygen in the pond. Todays there’s just over 11 milligrammes of oxygen dissolved in every litre of water in the pond – which is almost as much as it is physically possible to get in water at todays temperature (the techy term is that the water is 90% saturated).

This is enough for salmon or trout, the most oxygen demanding of fish.

So shortage of oxygen is not a problem at the moment. The leaves seem to be haivng little effect on the dissolved oxygen at present.

What will happen as the pond ages and more leaves fall? That will be interesting to find out. Will the pond get ‘worse’. Will it become a poorer wildlife habitat? I suspect not – but we’ll need to wait to find out.

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3 Responses to “Do leaves use up oxygen in garden ponds?”

  1. How much oxygen do I need in my pond? « The Garden Pond Blog Says:

    […] mentioned the other day that in my pond the water is about 90% saturated at the moment – enough for even the most sensitive […]

  2. Carla Says:

    I am reading this comment and am relieved! I live in Colorado on a property that has more trees then open spaces. Last year I begun to dig a pond close to two tall Colorado fir trees in our yard and I am worried that I might have picked the wrong spot. Matter of fact, I can’t find a better spot for it because there is a septic system and a leach field that has been installed in the area that is in the open and gets also the most sunshine around here. I just hope I wont have to fish for pine needles all year round.

    Carla

  3. Jeremy Biggs Says:

    Hi Carla
    Do you have a photo of your pond’s site? It would be interesting to have a look at it.
    J

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