Originally Posted by Termato
One question Byron, what do you mean using higher nitrates?
Are you trying to say that regardless of the nitrate levels you should do a weekly water changes due to things like Phosphorus etc.?
Regular partial water changes are necessary no matter what; the benefits are enormous [I really must get that article finished
]. There are several reasons for doing water changes, and no tests can indicate these. Nitrate is the one most often mentioned, and it is true that if nitrates that have been at say 10 ppm suddenly rise to 20ppm something may be wrong, but by then whatever it is has happened, and the effect on the fish has taken place. A water change then may relieve things, but the better course is to maintain consistently stable water conditions, rather than wait for trouble and then trying to fix it.
Prevention is preferable to cure.
Any tank with live fish, plants or not, will benefit from a regular weekly water change. The volume can depend upon the fish load, and if plants are present. I have always done 50% water changes weekly on all may tanks for 15+ years, and my nitrates are always zero to 5ppm depending upon the tank. Water stability is more certain with regular substantial water changes.