Fe in Water Column

[Jeffery Ludwig <jjl22 at drexel_edu>]

Right now I'm working on a high-light 15 gal, 55W 6400K PCF from AH 
Supply.  In order to prevent iron deficiency using (H. polysperma as an 
indicator), I'm dosing 1ml of Flourish and 1ml of Tetra FloraPride daily, 
weekly 5 gallon water changes.  This is an uncomfortable level of trace 
additions for me, I'd like to see my dosages around half of this.

I've been browsing around Dennerle's site and also referencing this with 
Scheurmann's text and have concluded that my lighting levels may be a 
little too high.  I've come up with three possible "mechanisms" for why my 
tank needs so much trace:

1) High light, high growth rates which causes high uptake rates
2) High light, high growth produces too much O2 which rapidly oxidizes Fe
3) High light causes photo-oxidation

Of these three I think #1 is out because my growth rates aren't 
exceptional.  Both Dennerle and Scheurmann mention excessively high oxygen 
levels being detrimental (redox is too high to keep Fe available).  Does 
anyone have any evidence of this?  Can there be too much O2 production and 
is this causing the huge trace demands in our ("American") tanks?  I've 
noticed the Germans and Dutch use lower lighting levels than us, might 
there be some benefit here?  But Amano's lighting in Nature World #2 is off 
the map; he's using 80W over 15 gallons?  My nitrate is 15ppm in the tank 
b/c of very high tap levels, can high nitrate levels increase trace demand 
(Scheurmann states this also)?

Wondering if he should run out and buy an O2 test kit,
Jeff Ludwig
Philadelphia