"thorny rose" wrote in message
...

hi all, i have a well established pond, had it for about 12 years now,
it measures 14ft by 9ft by 4ft deep and holds about 3145 gallons i have
two large filter boxes, a uv clarifier and a submersible pump which
shifts about 3000 gallons an hour it also has two smaller pumps
powering two waterfalls. the fish i have in it are koi, goldfish, orfe,
2 barbel and 2 catfish. we used to have really clear water but the last
2 years in late summer the water has turned very green and cloudy and
has a lot of particles in it. the pump is checked twice a day for
blockages. about 3 years ago the goldfish had babies, about 20 of them
and when they grew to a reasonable size i gave all but 2 of them away.
i dont think the pond is overstocked, all the fish seem perfectly
healthy but this cloudy water is driving us nuts. has anyone any idea
what might be causing it ? my partner insists each year that we empty
the filter boxes out and clean the media and the water does improve but
i'm sure by doing this we upset the biological balance of the filter and
as i'm now suffering from arthritus it's also becoming a pain in the
backside each year. if anyones got any suggetions on why this is
hapening and how to stop it i'd be grateful.


You have an algae bloom caused by excessive nitrates. Do you have any
water plants planted in your pond? The more plants you have, the lower the
concentration of nitrates you will have in your pond. Also, you can add
beneficial bacteria and enzymes to the water that, once established, will
out-compete the algae for nutrients and help keep the water clear. You can
obtain this product at just about any fish dealer or garden shop. And yes,
you should clean out your filters periodically and do periodic small water
changes. This should help, but at this point in time, it will take time to
clear it up.

George