ive been doing regular water changes, and cleaning and maintenence as i should, only have two fish. a rainbow shark and a danio. but it just keeps coming back. my 55 is completely algae free, visibly that is. n i know that plecos need other things than algae, thats why ive had one for five years now. sorry if i seem snappy, bad day at work. my other catfish and pleco are in my 55. i think i might go with the otos that gg suggested. thanx