PMDD recipe

Back by popular demand!

  1 Tbsp Chelated Trace Element Mix (7% Iron + B, Mn, Mo, Zn, Cu)
  2 Tsp K2SO4 (potassium sulfate)
  1 Tsp KNO3 (potassium nitrate)
  2.5 Tbsp MgSO4.7H2O (fully hydrated magnesium sulfate, aka epsom salts)
  300mL distilled H2O
  0.5mL 9M HCl (optional)

Dissolve the trace element mix in 150mL distilled water, then add the
remaining ingredients.  Add additional water to make 300mL solution.
The HCl helps prevent the growth of fungus and may be omitted if the
mix is kept in the refrigerator (sorbic acid may work better; anyone
care to try?).  Add enough mix to the tank every day
to keep the Fe level at about 0.1ppm (the exact amount will have to be
determined by experimentation, but 3mL per 100L tank water is about
right for a tank with rapidly growing plants).  Measure nitrate levels
regularly, and adjust the amount of KNO3 in the mix to maintain about
5-10ppm (this step is fairly important, and for some it may be more
practical to dose the macronutrients separately).  If test kits
are not available, satisfactory results can be obtained by adding 1mL
mix to 10L replacement water during water changes.  Most of the
ingredients can be purchased at hydroponics shops or garden supply
stores.  Epsom salts are available inexpensively at pharmacies.

If your local trace element mix has 4% Fe plus Mg (in addition to B, Mn,
etc), you'll need to modify the recipe slightly by omitting the epsom
salts and increasing the amount of trace element mix slightly.

With a little legwork, you should be able to get a lifetime supply
of the chemicals for about $25, much less if you get a few friends together
and buy the stuff in 50lb bags.   For a few hundred bucks you could
treat one of the smaller Great Lakes.
Kevin Conlin   kcconlin at cae_ca   "We're Canadians.  We HAVE to be polite"
Finger as332 at freenet_carleton.ca for PGP public key.