I always have a pleco or two and I'm surprised at how much of a difference they make. In my 240 I have 2 (about 10" or so) and they can purge my entire tank of algae in 2 days. Im only talking brown algae though. And I have a gravel substrate so thier messes are less evident.
A lot of people dont understand what plecos actually eat. I dont understand algae myself, but from experience plecos eat brown algae and avoid green and black algae. If you have a problem with brown algae, a pleco can help, if its green or black algae, theyre useless. Also, if you get rid of your pleco you may discover you have had brown algae all along but it was getting consumed fast enough that it never became evidennt.
You can always use plants or an algae scrubber to help out since theyll lower nitrates, which will slow algae growth. Magnets and scrapers and whatnot are labor intensive comparitively speaking, but effective. The only downfall is they obviously only reach the algae you can reach.
You can always pull your pleco out into another tank for a few days or a week or so and see what happens. If it stays clear youll probably be fine with out one. If brown algae shows up, you can always try alternative methods for dealing with it.