On Sun, 13 Apr 2008 17:17:47 EDT, Joan wrote:

Hi, ponders! It's that time of year again when I start re-thinking
how I've been managing the pond and nervously watching the fish
closely for health issues. I've been reading, which always confuses
me, so now I'm wondering:

Do you really have to do partial water changes in ponds if the water
chemistry is okay? My pond is probably about 1500- 2000 gallons, only
about 12 goldies, pH solid at aroun 8.5, alkalinity around 100, no
ammonia or nitrite, lots of plants, a good waterfall, a nice
mechanical/bio filter.

As Carol mentioned, lots of various answers, and your situation/environment
and water source all have to be considered. There are different things you
can get away with based on what kind of pond and fish you have. Koi only
ponds the latest is to do a continual flow, people are using carbon filters
for the input with the output flowing to water the garden in some way.

Those who mix fish & plants can get away with less extremism. How many fish
to gallons makes a difference. I feel I'm on the line in the koi ponds, so
I do a 10-15% water change once/week. The goldfish pond, with much less and
smaller fish, once every other week.

In my case though, doing a water change out keeps the buffering up,
decreases heavy metals and can reduce parasites & bacteria, imo.

Do I really have to drain the pond every few years for a major
cleaning, or can I just scoop the gunk up off the bottom with a net?

Better would be a shop vac, as all the gunk, plus fines, are suck out of
the pond. If you're just talking a few leaves not a problem. Draining the
pond is not a necessity, nor preferred, if you can keep the bottom clean.

It took so long to get the water just right; I hate to rock the boat.

That's why small frequent water changes are the mantra of most pond clubs.
http://koiclubsandiego.org/library/w...hange_outs.php

When I first got into ponding one of the senior club members compared not
changing one's pond water to staying in a room without opening the windows
now and again. Or imagine having your car on recir. air after you've just
taken the family out for a Mexican dinner. eg ~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us