Seawater Desalination intake - algae, lichen or mollusc?

[pv0203]

Hi, We're currently building a sizable seawater desalination, and the location where the intake is to be has these hard white shells with hollow centers growing on the rocks and wooden surfaces. There are also long (more than 10cm) green algae looking strands.

Would someone please let us know what these might be? We need to make sure they do not grow in our system. A suggestion on how to prevent them from growing (chlorine, biocides, etc) will also be very useful. Thanks.

[billw]

They're barnacles.

[pv0203]

That was quick. Thanks Bill!

[sara135]

Wow, i did/t know anything about it before... tnx