Tank is still kind of newish. Most important thing is don't freak out, and don't expect to fix this in a couple of weeks. Maybe bump up the waterchanges and siphoning of detritus for a couple of months and revisit the situation then. I battled cyano for what seemed like forever, then when I accepted it as part of the process, and learned to live with it, one day it just went away. At this point, the difference between test kits is not important, as you know you have nutrients because of the algae and cyano. How much don't matter much, aside from the fact that you want less. The phosphorous kit comes into play when you are ready for refinement. You ain't there yet. Keep doing what you know you should be doing, and let it play out.
-Waterchanges
-siphon crap
-blow off rocks
-modest feeding
-don't add any "supplements" other than the holy trinity as needed
-make sure your bulbs are good and run a reduced photoperiod
-Skim wet
-don't freak out