For about 4 years now, my husband and I have had No grackle poop in the pool. We still have grackles, but my husband stays on it. Our yard has a border (neighbor) of some type of Evergreen trees, roughly 18ft. high. When they start to flock and gather in them,he gives them a few days, then goes out with a pole that is 18 ft. long and knocks down all the nests. The birds do a lot of hollering, but leave the nest! He does not kill the birds, just blasts the nests to the ground, picks them up and throws them away. He also wears a hard hat when he does this, for the few birds who want to put up a good fight. He also gets the nest down before eggs are laid. He now knows the difference between a sparrow nest and grackle nest. The grackle nest is Long. He checks these trees once a week. A little time consuming, but we are free of those disgusting poop balls!