>> I'll second the part about not skipping water changes. In my tanks, even
>> with zero nitrates (or 5ppm after I add some), I still do weekly 25% water
>> changes. -- Chuck Gadd
>
> Thanks for all the good discussion about the nitrates.
> My main goal is not to reduce how often I change water, rather how quickly my
> fry grow. Does anyone have any input on the degree to which nitrate slows
> growth?
A bit late reaction but I wanted to point out that nitrate is not the
primary factor in retarding the growth of fish - the amount of growth
hormones in the water are. For fry nitrates are best kept below 15 ppm but
this can be easily accomplished (if you have enough light) with aquatic
plants. The growth hormones (and all kinds of organics you can't test for)
can only be removed with water changes.
The bottom line is, whichever method you use, there is never an alternative
for water changes.
Best regards,
Hugo.