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WATER TREATMENT-Phosphate, nitrate

Hello,
  My explanation of water treatment sure did generate some
questions.  Well, I had to look some stuff up (old college text
books sure are dusty) and talk to a few water treatment
operators to get the facts.  I hope I get it right this time.
  1. Phosphates are removed from water in the floc which
settles out in the settling basins.
  2. Nitrate is the most oxidized form.  Not the most reduced,
I had it wrong last time.
  Paul Sears wrote about nitrate contamination in
groundwater.  Nitrate contamination in ground water is a
problem.  A U.S. Geological Survey found that 9% of the
3351 home wells it surveyed had more than the safe
amounts of nitrate set by the Environmental Protection
Division.  The regulations now require testing for nitrates
once a year on water systems.  The maximum contaminant
level (which cannot be exceded) is 10 mg/l.
  3. Cynthia asked what is normal superphosphate
chemically.  It is Ca(H2PO4)2 and it is a raw material in
fertilizer.
  4. The difference between macronutrients and
micronutrients is the amount.  At least that is what they
taught me in me fertilizer class.  e.g. Boron is a micro
nutrient and it is applied at a very low rate of 1 or 2 lbs. per
acre or per 5 acres.  It is very hard to apply such a small
amount to such a large area so we mix it with other
macronutrients (N,P,K).
  5.  A Phosphate is used in water treatment do to high iron
levels in the water.  The Phosphate sequesters the Ferrous
ion and holds it in solution. This prevents the discolored
water and the problems with cloths washing that high iron
levels cause.  This sequestered form will break down over
time and you will get some ferric (insoluble) iron in the water
which will cause problems for the water system (this only
happens in areas where you have a water storage tank in a
remote area and the water sits for a long time).  Now, if there
is a "free residual" of Phosphate in your drinking water and
you add it to your fish tank and then put in iron fertilizer the
phosphate will sequester the iron.
  6. I disagree with the statement from Dr. Dave about "the
chief benefits of the substrate being its anaerobic state and
not its Cation Exchange Capacity CEC".  If this were true
plants (terestrial) would grow very well in all types of soil. 
The cec of silt, clay, sand and organic matter are all different.
The best soils have a certian mix of these 4 things. The best
mix grows the most in the way of crop production.  The sand
soil cannot "hold" (low to no cec) the nutrients long enought
for the plant to up take them.  Ask someone from Flordia. 

Paul L.   "May the force be with you".