If the plecos aren't eating it then it is probably blue green algae which is
actually a bacteria. check out
http://fins.actwin.com/mirror/algae.html#cyano

This can be treated with an antibiotic I have used Maracyn in the past ( see
http://www.petguys.com/pet-guys/-084942011100.html ) and it was very
effective.

This is usually caused by poor water quality.

"paul anderson" wrote in message
news:AbYqe.1448$5s1.234@trndny06...
I just started a 40 gal planted tank 4 weeks ago and about a week ago i
started getting green alge on the front of the glass. I have 2 4 inch
plecos in the tank but they are not eating it. I just added a CF light and
I am running about100 watts. The water temp is around 75 and all my levels
are perfect. Is there any thing other that i can add to the tank to take
care of it. OR am i gonna have to scrub every other day.

Thank you in advance
Paul