I love it when something new grows in my tank, even if it is something that many people think is a plague. I just find it interesting. This is the stuff that stirs my interest in this lifelong hobby.
This stuff started growing on my rocks a few months ago and at first I thought it was some type of coral. It turns out it is some sort of invasive bubble algae but for some reason it is not that invasive.
It only seems to grow in certain places and I think it makes the rock much more facinating. I really don't like the look of new, clean, sterilized rock and know that if my rock ever gets like that I know something is wrong.
This is a DIY, hollow cement "rock"


Here is another piece with a little tuft of hair algae growing on a frayed string. It is the only hair algae in the tank and I also find that interesting so I leave it alone.



There is very little algae in the rest of the tank but I do have a nice growth of short turf algae in some places. This comes from where I collect rocks and water in the Long Island Sound.

It can become invasive when it take over your tank. The are filled with many many spores. When popped the wil start to grow everywhere. With bubble and hair algae you def have to many phosphates as well as nitrates being pumped into your tank. I would recommend more export than import. You might also want to consider a green emerald crab.

I actually have some emerald crabs in there. They hate the stuff but they are interesting. That little piece of hair algae died but I don't worry about that or nitrates.
The tank is very old and so far, nothing has taken over.
That bubble algae seems to only like the rocks I built from cement which I find wierd.
My algae trough is filled with a cement coated screen and the thing had so much of that bubble algae on it that it over flowed and I had to clean it. It appears that cement adds something to the water that certain algaes prefer. probably silicates.
I am not sure but I find it interesting that some things prefer the cement rocks. Some of those "rocks" have been in there for 20 years so I am surprised that there is still anything leaching from them. There is absolutely none of that growth on any rocks other than cement rocks. I have not noticed that until now. Very interesting and cause for an experiment.
And I just love to experiment.