Hey most pleco suck IMO, they only eat algae till they realize pellets and meaty foods simply taste better. Pleco just add to the waste production....better be safe the sorry as most plecos don't cost nearly as much as rays.
However take this opportunity to try and fix the algae problem with other methods:
-Are you adding prime or other decholirnator when doing water changes?
-How often are your lights on? How strong?
-Overfeeding?
-More water changes (unless your water changing schedule is good already)
-Invest in a uv sterilizer, a good one.
-Invest in a algae scrapper or make your own. (Youtube it)
Hope this helps!