That would be 400 gal/week. This would cost a lot. Is there no
alternative? Perhaps filtering with charcoal?

- Francis

"~ janj JJsPond.us" wrote in message
...
I have a 4000 gallon pond (filled 8th May 2005) with 12 koi about one
foot long each. I have not had any amonia or nitrite problems. What are
the pros and cons of partial water change? How will it affect water
clarity etc.?

My tap water is soft water at pH 7

Jugglingeek
http://homepage.ntlworld.com/jugglingeek

The pros are that heavy metals, salts, hormones and such will build up
over
time in a pond that doesn't have old water out, fresh water in. The mantra
of the koi world is "Frequent Partial Water Changes" 10%/week on average
to
their specifications. Of course the water source has to be consider. Is
your tap water normally soft or going thru a water softener? If going thru
a water softener, the type that uses salt? If naturally soft you may have
to use baking soda or other material to keep the buffering up when you do
a
water change.

The best stuff to read on water chemistry in a nutshell is he
http://www.vcnet.com/koi_net/H2Oquality.html
Straight to Water Change Outs from same website:
http://www.vcnet.com/koi_net/finalnet.html#waterchange

Is that you juggling? If so, how's the neck? ~ jan

See my ponds and filter design:
www.jjspond.us

~Keep 'em Wet!~
Tri-Cities WA Zone 7a
To e-mail see website