Quote Originally Posted by FireWater View Post
I have never experienced hydroids first hand so I am not 100% sure. I believe that they have a free swimming stage until they attach to a good spot for them.

Sounds like a good plan on removing the algae.
I'm not sure but they look more like the jellyfish here(below hydroids):

http://www.chucksaddiction.com/hitchodds.html

Are they a pest? I have been taking out the ones I see on the side filters of mi tank.

My tank has two side filters like the ones on the back of an all in one cube. There used to be sponges, bioballs, etc. in there but I have removed everything. I left the return pumps though, so there's still waterflow in there. I guess it makes a really good place for all this things to grow. I have also found flatworms there but anywhere else in the tank(I have 2 sixline wrasses). There's also lots of copepods, amphipods, etc.