The first garden pond

When is my pond going to stop being pea green?....................(the answer is coming soon)

I thought it was about time I showed you my first garden pond. So here it is about 1 year after construction – a rather soupy green – in April this year.

The pond is almost entirely rain water fed, with perhaps a tiny bit of runoff from the garden around it. We’ve only added clean washed sand to cover the black plastic – so very few added nutrients (except what’s in the rain water).

I know the water is pretty clean from the exceptionally low conductivity of the pond – conductivity is a measure of how much stuff is dissolved in the water and is an excellent rough guide to the state of your pond – much more important for understanding its condition than dissolved oxygen or pH (but more of this another time).

My pond has a conductivity around 80 – 100 micro-siemens. Micro-siemens are the units that conductivity is measured in – literally a measure of how much electricity the water conducts, which increases the more stuff is dissolved in the water. Sea water – which has lots of salt in, has a conductivity of 30,000. About the highest reading you could get in badly polluted freshwater would be 4000-5000.

The conductivity of one of Britain's cleanest lakes

For comparison here’s my meter dipped in Loch Morar in Scotland which is both Britain’s deepest lake, and one of its cleanest. The conductivity is 42. In lowland England the average around the ordinary countryside where most ponds are polluted is around 600 – to have a pond in the Oxfordshire countryside with a conductivity of 100 would be exceptional (that is, exceptionally good!).

So clean water doesn’t guarantee you instant clear water. But it does come, eventually (more news on this later, too).

By the way, Zoe and Katy are looking at the frog tadpoles.

Tags: Garden ponds