What is this?

[minotaur]

This starts out as a small shiney ball, gradually gets bigger, then expands with greenish armlike things

 

[Hara]

valonia a.k.a. bubble algae

this is a nuisance algae that can quickly take over. removal of it should be done carefully, without breaking the bubble. The bubble contains spores and it will spread dramatically after breaking open a bubble.

If it is possible, take out the pieces of rock that have it and remove the algae.

 

[minotaur]

It is not possible to remove the rock, some of it is in low spots in the tank. Most of the bubbles have burst. So can i just grab ahold of the thing and pull it out?

I have at least 4 that i can see. Is there a way to prevent them after I get out the ones that are already in there?

Thanks for your help

 

[Fluff]

Is there a way to prevent them after I get out the ones that are already in there?

As with any nuisance algae, your best defense will be extra water changes to remove any traces of phosphates in your system and starving it out. You can try to twist it off but in the crevice you have it growing, that doesn't seem like an option since it probably would just burst on you. And as Hara has said, removing the rock is best when trying to remove the algae. This gives you more control and you can rinse the rock in sw before replacing it. Since that isn't possible, doing a few extra water changes should help.

 

[dorian965]

try using vacum - siphon when doing your water changes and hold it right on that spot while removing the algae, maybe.

 

[minotaur]

ok, thanks for your help