Posted: 08/06/2013 at 22:17
I'd stir it up slightly to left the sludge from the bottom and do a particle water change. Do this a couple of times, from now til late August and over time your pond should become clearer.
Really you shouldn't clean ponds by emptying the water fully. This upsets the balance and causes many problems. If possible use only rain water to refill, as tap water can start algal blooms.
Failing that, fill buckets/tubs/kids pools with tap water and let it sit for a week or two. Get yourself a big sieve to strain and catch any wildlife, and count the buckets of water.
This is the best way of changing water without too much disturbance.Oh, and don't go crackers when you start to stir up the sludge.