Nitrates are just one of the pollutants that you are water changing to
dilute.
That said you prob let it go for a lot longer with a small bio-load.
I try give all me tanks a 25% every week
yes thats a lot of water changes
but once your in the rythm it's kinda a workable method
Put it this way, it can't hurt to keep up the changes.
But you can get away with not doing them for longer
I have a marine tank that has been 6 months without a water change
nitrates are maybe 15ppm
But I do plan on getting stuck in a doing a nice big one next week
Is a tricky tank to water change is all
even so
zero cassualtys
I wouldn't reccomend others doing that but yea I have gotten away with it.



"Brian" wrote in message
...
I have a large tank with a light fish load. My nitrates are around
10PPM. Do you need to do a water change with such low nitrates?

When I had a heavier load I would water change enough to keep nitrates
below 40ppm but since my load is lighter the levels of nitrate are
taking much longer to rise.

Brian