Zack: I would do the following:
1. Follow the recommendations in terms of light provided by Ed (Big E). Once done, leave it alone. Dont make any more changes.
2. Sometimes SPS systems take a long time to stabilise...the presence of Cyanno in absence of organic Carbon dosing (like Vodka) suggests instability with the system...Your PO4 test kit is useless...see below...but even with the presence of some PO4, you shouldnt really get Cyanno in an estalished systtem...IMO systems generally over 1 year can be said to be stable and established for SPS corals.
3. I use Salifert test kits for Alk, Mg, and Potassium...BUT salifert is USELESS for Phosphate...I get a 0ppm reading on that kit when Hanna and Elos High Resolution kits read around 0.05ppm from the same water sample! Saliferts Pottassium test kit is IMO the best out there.
4. Your Pottassium level is fine...if it is really at 360ppm then its not bad at all; K only needs to be dosed on Zeovit systems.
5. Dont go too aggressive on the GFO...go easy and siphone out whatever Cyanno you can.
6. No need to add trace elements and or other potions. Keep to the basics, and keep the alk, ca and mg consistent and hopefully colours will follow.
7. Feed your fish well. Obviously dont grossly overfeed, but feed them well.
8. If you can borrow a PAR meter, I'd use it to MAP out the PAR levels in a diagram so you have it for future use, and use that info for placing corals appropriately.