What about the floating plants @ceg4048 ? It seems logical to me to fix the issue thats showing up with the non CO2 limited floaters before one starts tackling any algae issues. Of course you could do both at the same time but you cant discount those white floating plants as a problem too.
Honestly I can't really see anything wrong with the floaters in post 15, but choosing between solving a trace problem, if it exists, and a CO2 problem - well, I always choose to tackle CO2. I mean, really, it there is a shortage of trace then just add more trace. That is so simple. I never worry about traces and I never have trace problems. All this hand wringing about Iron. I never even bother to worry about what chelator I'm using. Whatever I have is good enough. Seriously, I can't even remember when was the last time I had an Iron deficiency.
On the other hand, look at the devastation being caused by the algae. That'll not be easy to fix as just adding more CO2.