Valonia and Emerald Crabs

[Beverly]

I've noticed a couple of patches of valonia getting bigger over the last week or so in our 42 gal hex. I have heard that emerald crabs will keep this stuff under control, and the lfs has some for sale at the moment.

Anybody with experience adding emerald crabs to control valonia? Will they eat the food I offer the fish if/when the valonia is under control?

All comments regarding emerald crabs in a reef will be much appreciated.

TIA.