Answer:
Hello, the pool will be full at 12:30 PM. 1200 gallons is half of the capacity of the pool (2400), and the pool was half full at 10:30 AM after being run since 8:30 AM - two hours. This means that the pool will only need two more hours to fill up, and it will be full at 12:30 in the afternoon.
Have a great day! - Mani :)