Why is it only in Overflow ?

[Lesley]

hi, last night I decided to get on a ladder and look inside my overflow. (not a pleasant experience) lol
I nearly died, I have green bubble algae. There is 2 clumps about the size of a fist growing happily.
I don't have any sign of it anywhere else DT or Sump ?
Is it a concern ? Should I remove it ?
And last question is why does it grow in the overflow box only and not anywhere else. ???
I actually still have some GHA in there as well, but that has been there for a long time and its never spread anywhere else so I have just left it alone.
Is bubble algae a sign of excess nutrients like most other algae ?
Any advice would be greatly appreciated.
thanks

 

[alpineroush]

It is a sign but it also like a small refugium as long as it's not in your dt

 

[Bad Company]

Bah,
your CuC can't get at it in there. Algae does not "spread". It grows wherever conditions are favorable, and it doesn't get eaten.