I am reading this and pulling whats left of my hair out.
It took me two full days to fill my 72 with RO. I have used stricktly RO for WC and top off, and my tank has algae, cyano and I have flow like a tonado in there.
However, my AP24 was stared with petco NSW, and ro for Top off and WC, and I have never seen algae in the tank. there is also no skimmer on the ap.
I dont think that there are set rules in this hobby. I think people put too much stock in "the rules" and I am also starting to think that the only no fail plan is NSW, even local NSW, like in my 6 gal at work. No algae, or any problem at all using murky bay water from day one.
JMO