N03 and water changes

["Steven Maier" <stevemaier at ameritech_net>]

What other than excess nitrate will accumulate in the aquarium between water
changes? Using my Hagen kit I have not been able to measure Nitrate yet. As
my PMDD dose is now closing in on my target FE level I have resorted to
dosing additional KNO3.
As I was changing 33 % of the water each week I found that I was under
dosing the replacement water to a place that the FE became unmeasurable.The
only problem I have is some hair algae. I am considering a smaller water
change. What would be the right thing to do here.
1. Increase the PMDD dose after the water change Y/N
2. Decrease the amount of the water change Y/N
3. Decrease the frequency of the water change Y/N
Also what might be a target or max reading for NO3
Thanks
Steve