BFLP:
I assume you are referring to Filamentous Algae ("FA"), also known as pond sum or moss. Grass Carp rarely eat FA.
A quick search for "Filamentous Algae" in this topic alone leads to about 40 threads discussing FA and possible chemical and biological controls. Among the latter, the (annual) stocking of Tilapia is perhaps the safest/most effective method of FA control. Off hand, I do not recall anyone posting wrt Tilapia in Kansas, so I don't know what your local availability or legality (some states control Tilapia, some prohibit) is. Here is a link to the search results:
FA Search For reference, could you tell us the approximate size of your pond is and roughly how much of it is covered with moss/FA (% of surface or perhaps % of shoreline and a width it extends out from shore)?