Firstly thanks Prof for your reply and thoughts on using the existing system with some mods.

After another week of no improvement after using "Clarity" "Purigen", carbon and a 25% water change (slow change with R/O supply) I broke down and went to the LFS yesterday and picked up a Mag 350. I installed the micron cartridge and 1/4 cup of DE, turned the system on and within minutes the filter turned dark green, not hunter green but more like olive drab green. This must be a single cell algae issue right?

I have turned the lights off for today and plan to continue using the Mag 350. The water was a little clearer this morning after running all night with the Magnum but not much. (This is a 180 gallon tank though...)

My water conditions are
pH: 7.1 When the C02 is on (7.8 when it's off over night)
KH 5.5
GH 8
Phosphate 0-.25ppm
Nitrate 10-15ppm
Amonia 0-slightly readable on the scale (.25 or .025 can't remember which)

I am open to thoughts on how to "reset" the system including the 3 day blackout if necessary. The problem is I don't know what caused what now appears to be an algae bloom. I do not have excessive algae growing on the glass or plants, the plants are doing very well as are the fish (great color etc.)
Aaron