Why isn't my coraline algae growing!

[Timbits]

What do you think of my theory "that there may be very little trace amount of copper so when i first add a frag, i get good growth but then it slows down later on?"

OR if copper is a problem, would i not get growth at all right from the beginning and the coral will just die?

I have a paly that started with 1 polyp that has over 100 polyps now that has been in the tank since the beginning...