Your math is very close but 1-2 lifts per day being a good number has to be achieved over several hours regardless as running it an hour would agree with the math but respiration would more than reverse that 1 hour. Lifting numbers are only part of the equation. In your case I would put it on a xmas tree timer ($15 at Lowes) and run it 6 hours at night to see if it settles. Since your pond is only 2 years old the o2 demand should not be great. Try this along with the jar test. Any chance the 25% with no stone apron has soil coming back into suspension at that area or is that a beach area? Also if your pond has only had aeration for a short period of time it is still "finding" itself as newly aerated ponds have a transition process to go thru..
