"Rod Runnheim" wrote in message
...
In a healthy planted tank, the changes aren't to deal with Nitrate
levels,
but to add trace elements that would otherwise be lacking and are not
typically added as a fertilizer. There is probably a way to find all of
the
trace elements you would ever need and dose them carefully (based on
current
levels) and obviate the need for water changes. This would be terribly
complex however!



So... on average- how much how often?


--
Toni
http://www.cearbhaill.com/aquarium.htm