Persistent Algea

HI all!

I have had a clean tank for over a year now, but all of a sudden I 
started getting some "nice" looking algea growing on the bog wood.  I 
say it looks nice because it was really *thick* and looked like peach 
fuzz(1/8" long).  At first it stayed on the bog wood, but then migrated 
to the plants.  Usually the oto's can take care of any algea in the 
tank, but this was too much of a task for them.  When I removed one of 
the amazon swords and tried to remove the algea, I could not even 
physically remove it, pulling on the algea would rip the plant it was 
attatch so strongly.

Does anyone know what this is?  Or how to get rid of it?  My tank is 
heavily planted to the point I cannot clean the gravel.  Since this 
bloom, I have removed all the plants, added a soil substrate, and 
replanted the plants after pruning the heavily covered plants.  I have 
4 48" tubes for lighting that are turned on for 11 hours/day.  I change 
50% of the water every other week.  In this 55 gal tank, there are 
about 18 fish which include about ~8 oto's.  I have also started adding 
CO2 since then.