How to carry out a partial water change.
As koi keepers we are experts in keeping fish in an
enclosed artificial environment that is stocked with an
unnaturally high stocking level and fed a relatively
large quantity of food. Consequently, there will come a
time when the pond's ecosystem becomes unbalanced,
requiring our input and intervention (yet again).
- Yet over a longer time frame, (weeks and
months), our pond water will naturally start to
accumulate a multitude of other processed
by-products that if our pond was natural, would
simply be processed further and taken up by other
living organisms in and around the pond.
- These intermediary compounds are quite safe at
specific concentrations in a pond (usually measured
in parts per million) but over time, could
accumulate to levels that would begin to adversely
affect our koi directly, or indirectly by
unbalancing the pond environment.
- Another reason for carrying out a partial water
change is to add minerals to a pond that may not
have had the benefit of regular clay treatments.
- You can use a combination of information gained
both visually and by your test kit to determine
whether your pond would benefit from a partial water
- This is the 'bank' where the nitrogen from the
ammonia is ultimately deposited, increasing in
concentration as more nitrite is oxidised into
nitrate by bacteria in the biofilter.
- Other cumulative compounds (sulphates,
phosphates etc) will have a tendency to accumulate
but rather than test these individually, use the
nitrate test as a useful benchmark (i.e. if the
nitrate levels are increasing then it is highly
likely that the others will be also).
- The water purifier will intercept and retain any
undesirable contaminants in tap water that will also
accumulate in your pond, causing stress to your
- The alternative to using tapwater that has been
passed through a purifier is to add a quality
tapwater conditioner to raw tapwater.
water pond "water
change" nitrate "partial water change" "nitrate levels"
purifier koi tapwater accumulate filter "tapwater
conditioner" ppm compounds environment click to read
pond articles here
A to Z
10 steps to a great koi pond
New pond care