getting a pleco to fix an algae issue isn't what will work. first you need to find the reason why you are having the algae bloom. cut down on food to limit excess nutrients in the water, less lighting etc..
I agree, find out what's causing the algae first before buying a fish to solve it.
Even a plec won't keep your tank 100% free from algae & they are poop machines so you could end up with more cleaning to do