Martin,
I used to use Interpet Pond clear I think it was called (pink powder in a green and pink box). This worked really well but was a bit expensive as it had to be done 4 or 5 times a season.
I then followed Alans advice on this forum and built a trickle tower (see attached link) and have never looked back. http://koicymru.co.uk/ponduk04.htm
I also work for a construction company that deals with the water companies and they have the same problems as us koi keepers in that they have to release clean water into the streams and rivers after treatment.
They use a trickle tower on a large scale to reduce nitrates from the water.
This is one we built in Fakenham by the racecourse.
Note the air intakes around the bottom.
This picture below shows the rotating distributor arm powered by the water pumped into it and the media bed. This filter can cope with flows up to 120l/s. Glad it's not on my electricity bill!!
And again the same filter after about 4 weeks to mature in warm weather.
Hope this helps.
Andy
Posted on Mar 31, 2006, 1:25 PM from IP address 213.120.71.165
