JM :

One thing to be sure about first. If your fish kill was a result of ag chems. from next door and they get into your pond bottom you need to be sure what the result will be if you stir them up again via aeration. Aeration should help your pond with problems from high productivity swings and DO problems. Good luck and let us know. You may want to run your situation by one of the aeration pros on the forum by email or they may see it here and reply.