[bertoni]

The pH of half-saturated limewater should be about 12.24, since fully saturated lime is about 12.54. If the limewater were dripped, the system might be okay, but it's hard to judge because a lot depends on the aeration and how quickly the limewater is mixed into the system. Adding a large volume at once can cause a locally high pH, which can lead to precipitation and perhaps injure some organisms.