Where did all the iron go ?

Help I am starting to run thin on ideas, and I am hoping someone 
might have some ideas I can try. I have a 180 gal full high tech tank
that is producing more frustration than plants :( 

Let me give a little history for those of you who have not already been
providing ideas for me to try. I setup the tank roughly 6 months ago
as an optimum tank (CO2 injection, PH controllers, Dupla heating and 
Dupla tabs/drops). I have included the full details on the setup below
as reference. The problems that I have been having include:
	* Lack luster plant growth (Val, Hygrophila Polysperma doing well)
	* Lots of "red/black" algae covering the leaves
	* several great plants (from George) dead or dieing (sorry George).
	* Virtually no trace iron detectable

I am starting to focus on the lack of trace elements as maybe the problem.
It seems that no matter how much iron I add to the system, I can't get it
to measure. I know... test the test kit, I did. I have a 30 gal plant tank
I have just setup that is doing great (even with UGF) that measures out 
just fine. I have been adding ~20-30 Dupla drops a day to see if I can 
make a dent (little luck). I just added ~150ml of ferro vit to see if it 
made a difference (Note: they recommend 2.5ml/10l). I was able to get a 
trace of iron after adding it (maybe 0.05ppm). I don't have test kits 
for any other trace elements so I don't know if it is just iron or 
across the board. However, cutting the lighting back to ~6hours seemed
to help clear up the algae and even some of the plants seemed to respond;
this to me would indicate that the tank is seriously short on something.

The tank is setup with the following:
    * The tank is 2'x6'x2' with an open top
    * (8) 4' 40W bulbs arranged in an overlapping pattern, 5" over the open top.
      Two of the lights run from 10am-10pm and the rest from 10am to 9pm.
      The bulbs include:
             ************************            (GE)
             ************************            (ultralume)
                      ************************   (ultralume)
                      ************************   (triton)
             ************************            (ultralume)
             ************************            (triton)
                      ************************   (ultralume)
                      ************************   (ultralume)

    * Dupla ungravel heating (on/off timer as controller)/Ebo-jager 
    * 4" of TexBlast with Dupla Laterite in bottom 1/3
    * W/D filter, there is a float in the sump that keeps the water
    	level constant (water changed at ~80-85F).
    * CO2 injection with sandpoint controller
      	note: I use a Magnum 350 as the reactor
    * water changes ~5gal twice a day at feedings
    * Daily Dupla Plant drops (25drops)
    * DuplaPlant tabs at any big water changes

The chemistry is:
	* PH 6.8  	(Kordon & Sandpoint)
	* GH 6.5   	(tetra)
	* KH 3.5   	(tetra)
	* CO2 14ppm 	(Lamotte)
	* Nitrate/Nitrite/Ammonia -Low to zero (kordon)
	* Iron ~0.05ppm (Red Sea)
	* PO4 0.1ppm	(Red Sea)
	* Temp 82F

The fish load is moderate with 7 SAEs, 5 otto's, 25 cardinal tetra's, 4 clown
loaches, 3 cory's, 2 large angels and 3 discus (I know I shouldn't keep the 
discus with the angels, but they have lived together for over a year).

Any suggestions would be welcome.

Ted Fidder
   (fidder at drmail_dr.att.com) (303)-538-5106
   AT&T Bell Labs
   Denver, Colorado