Just started mixing PMDD. The recipe I'm using says to closely monitor Iron
levels, keeping it at about .1 ppm. Question is, is this really needed, or is
there an alternative, as I have never seen an iron test kit. Shouldn't
monitoring nitrate levels be sufficient?

No, monitoring nitrate levels isn't sufficient. Nitrate is produced by your
fish, and the fish food that's put into the tank, so you could have plenty of
that while being out of iron. Alternatively, you may need to add extra
nitrate, if you have a lot of fast-growing plants.

However, there is an alternative. Many people recommend that you just monitor
the growth of your plants...particularly the fast-growing plants like frogbit
or Hygrophila. They will show iron deficiency first. If they start to look
pale, you need more PMDD.


Leigh

http://www.fortunecity.com/lavender/halloween/881/