Although I can't say for sure, this is my situation.
I have a biocube 29. It has the stock lightning, which (excuse my forgetting the wattage) includes a 50/50 + Actinic. I dosed 5ml of CA and ALK everyday. Each day i would test to find 7dkh, and 360 ca. The more i dosed, the more grew.
Today i have updated the lighting just a hair, to full 10k + actinic. Still PC lighting though. I still dose about 5ml, but now it is once a week. My coraline growth and existing coraline has died off. Its still crazy purple, but now my red coraline is cracked out. Growing like mold in a coffee cup.
My plan now is to keep ontop of the dosing (since i've been slacking) and verify whether the purple stuff comes back. Then ill know what kind of effect the lighting had.
Problem with all of this is that I have only had my biocube for a year now.... so this could all be the result of a maturing tank.
On a side note, i used one single flake of purple coraline, crunched it up in a morter and poured in my baby Fluval Edge tank. Since (and weekly 2 part dosings) the coraline has exploded in there. It has gone from a baren wasteland to full blown purple spotted crazy looking tank in less than 3 weeks.
To me... the only pattern i can see between my tanks and friends' tanks... is care. I work on my tanks every single day. I test everyday for EVERYTHING i can (reliable ones that is). I stir the substrate, i scrape coraline, i magfloat the crap off the glass... Dose when i remember, and phyto when i can. So far, over 2 tanks and over a year now... everything seems to be working.
So before i jynx myself to much... that is all. G'day!
*small tank with the yellow fella*
*big tank with the starfish*