plant

[leesanhua]

are they good or bad?

 

[TCTFish]

The first picture looks interesting but both seem to be hair algae none the less. This stuff can easily get out of control with absolutely no help from you. Pick out as much as possible by hand. Reef hermits, cerith snails, an algae blenny, reef safe starfish and if you don't care much about any coraline algae, a sea urchin would eat the stuff you can't get to. Collectively as a whole, they make a good cleaning crew.

 

[steve-s]

Looks like Bryopsis to me. No critters are known to eat that stuff. Manual removal and strict control of water quality is about the only means of controlling it's growth.

Cheers
Steve