Non sterile carp would take over your pond.
Grass carp, if not triploids (three sets of chromosomes instead of just two) still will not spawn in a lake or pond. They require about 150 miles of flowing river without interruptions like dams or weirs to successfully spawn and recruit young.
So sterile or not, you have in a pond the number of grass carp you put in less any losses to predation or mortality.
Now, put in too many grass carp in the wrong kind of pond (shallow, mud bottom, wind blown) and they will turn your clear, weedy pond into a weedless mud hole.
This much I have learned....you CAN fish for bass successfully in a clear, weedy pond. You CANNOT do so in a mud hole. Be careful how many grass carp you use. Control is the idea, not eradication.
Plus, Meadowlark is right one, grass carp eat some weeds much better than others and will starve before eating some things.
Good for carp, Hydrilla, Brazilian Elodea, Sago pondweed, Southern Naiad
Carp will hardly eat, Coontail (both kinds), Eurasian Milfoil, algae, Chara, most emergents