My dissolved oxygen meter
The latest period of icing-over again raised the oxygen levels in my pond.
This week I’ve measured up to 18.3 milligrammes of oxygen in each litre of water – this is more than can actually dissolve in the water, a condition known by specialists as supersaturation.
So the pond has an abundance of oxygen under the ice.
This means that the high oxygen levels we saw earlier in the winter were not a one-off.
How unusual is this pattern? I don’t know – because nobody has every carefully measured how much oxygen there is in garden ponds.
I suspect our pond may be a little unusual – it’s got a very natural, saucer-shaped, profile – the sort of thing you see in naturally formed ponds (garden pond edges are very steep usually), and large parts of it are very shallow.
It also has an encrusting layer of algae across the bottom of the pond – which have grown amongst the thin layer of sand we put over the bare butyl liner. The clear water means that these algae are probably producing a lot of oxygen.
We also have banks of moss in the water – also presumably contributing oxygen to the water.
Anyone within 20 miles of Abingdon who has garden ponds they’d like to volunteer for some oxygen measurements – we’d be interested to hear from you!
