This just appeared

[Mrs. Limpet]

My tank is new, almost 3 months. Parameters are good. Corals, fish, shrimp and snails are happy. A few days ago these white things appeared, and now have spread and I've noticed on a second rock. I'm not sure what it is or if it's harmful, any help is appreciated. Thank you. 

[Xanthine]

Looks kind of like ball anemones to me. (And like most hitchhikers, some say good, some say they are bad, but I think in general ...mostly harmless?)

[Joevember]

First are colonial hydroids and the second are pseudocorynactis (aka ball anemone). 

There aren't a lot of good ways to deal with colonial hydroids. A good way is to stop broadcast feeding if you're doing that.

[Mrs. Limpet]

50 minutes ago, Joevember said:

First are colonial hydroids and the second are pseudocorynactis (aka ball anemone). 

There aren't a lot of good ways to deal with colonial hydroids. A good way is to stop broadcast feeding if you're doing that.

Do you mean broadcast feeding the coral or fish or both? I currently target feed the fish to be sure everyone eats, including my shrimp and I target feed corals and broadcast any left over along with phytoplankton. 

[Joevember]

6 minutes ago, Mrs. Limpet said:

Do you mean broadcast feeding the coral or fish or both? I currently target feed the fish to be sure everyone eats, including my shrimp and I target feed corals and broadcast any left over along with phytoplankton. 

Hydroids eat small stuff floating around in the water. They aren't that much of a problem, more of an eyesoar. I have a bunch on my coral skeletons that don't bother them much. Just try to minimize how much they can eat if you don't want them spreading more. 

[Mrs. Limpet]

35 minutes ago, Joevember said:

Hydroids eat small stuff floating around in the water. They aren't that much of a problem, more of an eyesoar. I have a bunch on my coral skeletons that don't bother them much. Just try to minimize how much they can eat if you don't want them spreading more. 

Thank you.