"James Ervin" wrote in message
...

Makes perfect sence......now it fits. Nitrate is a marker for a need
to change water for the more potent DOCs.

Thanks.

If you don't have plants. If you do there may not be any direct
relationship between nitrate and misc. DOCs and other material which may
build up in the water. Hence most people change water regularly, even
people who have stable heavily planted tanks generally change water at least
once in a while.

Bob