One POSSIBLE explanation for little change in pH is the pond being fairly new, with little decay or plant respiration of CO2 causing acid formations that would normally lower morning pH readings in the absence of alkalinity and calcium/magnesium acid buffers..
I am a bit perplexed that pH is over 8 and the statement of "I know in SW AR you lime just about everything". If there are gravel pits in the area, are the dolomitic limestone?
