It a pond that size you might have water movement throughout the entire body of water no matter where you put the diffuser. There's a guy in Minnesota that runs his aeration right through the entire winter and his LMB do very well. Maybe it's because they are used to those conditions?? I don't know - I am not an expert. But I have been told on here many times that the science of winter aeration is far from complete. Please post what you end up doing and then post some updates and results as well. Not many folks with frozen over ponds posting this kind of info.