coralline algae in 5month system

[reefnut]

tank had nickel sized patches of the stuff at four months and now it has all turned white and shrunk to pencil erasure sixe.Doesnt apper to have been eatin.How do i get this stuff to grow?


33 gallon
25 # lr
2 1/2 inch lsb
1 domino damsel
1 peppermint
1 emerald crab
1 turbo snail
1 small anemone(i thinks its a condy)
tons of macroalgae(sawblade lookin stuff)

levels r good calcium at 420