How do I get this stuff under control! It is starting to form en masse
right under the water flow of the filter and on the leaves of one of the
older plants. Some of these strands look to be longer than 1/2" long. Here
is the set-up

55g freshwater
600 gph filter
pH approx. 8.0
ammonia 0
nitrite 0
no CO2 infusion, several life plants

It is questionable whether a common pleco put in a few days ago is doing
anything with it -- it appears that some patches have disappeared though,
but not significant enough to make a determination.

I hate to put chemicals in the tank to get ride of the stuff. What kind of
fish can control this algae? More plants?

Right now there are only a few fish in the tank -- 3 dwarf gouramis and 2
guppies. Had a massive die off about 2 weeks back -- unknown cause --
approximately 10 smaller cichlids died within 3 days. Ammonia and nitrites
never spiked. Should the pH of the water be brought down? Water temp is
75F.

Please help before I am looking at a algae filled tank.