Do you currently have in a 1/3 acre pond 800 2in. fish ? Tell us what concerns you about turning off the aerator - any specific matters as to your pond. You should not have a DO problem (absent pond specific matters)under current weather conditions with that small amount of fish mass, if you turn off or slow down the aerator for a few days. How hard would it be to turn it down and raise it off the bottom (to about 5ft. deep) to see effect on water.