02/05/2014 at 09:25
Unless your pond is *huge* (mine is 2,500 litres and not large enough) buy barley straw extract. You can get it easily enough online or at a garden centre.
There is an idea that you can put the barley straw itself into your pond - you can. But all the expert guides I've read say that this wont work (can't remember why - there was a good reason) unless you've a huge pond.
That said you noticed the extract working within 24 hours and repeated applications as prescribed seems to be keeping our pond crystal clear.