Lets talk Valonia

[High tide]

I guess it's all luck of the draw, you never know if they'll eat valonia! I have had great success with emeralds, you need enough of them to do the job. Also, with fish you never know, you could have a tang or a rabbitfish that eats them.
I have 2 tanks plumbed to the same sump, one tank has valonia the other tank doesn't, the sump has it too. The tank that doesn't has 4 scopas tangs,2 yellow tangs, a powder blue, and a coral rabbitfish. The tank that does(being eliminated through manual removal and emeralds)has 1 yellow tang,1 scopas,1 double barred rabbitfish, 1 striatus tang, and a blochii, none of these guys touch it.
In the past I had a powder brown that eliminated all traces of valonia in a 135 gal. single handedly.
I've noticed my emerald crabs picking at my SPS, but they never seem to do any damage.
Good luck in your battle!