Its too late for this option now, but something to consider in the future - should you need to transfer any more water to the upper pond.
Consider constructing a wet well between the two ponds that is gravity-fed from the lower pond through a surface-channel or high-capacity pipe. Place your pump's intake in the wet well, along with several suspended burlap bags ("tea bags") that are filled with aluminum sulfate during the pumping-process.
This isn't tried-n-tested by any means; but it just might help drop the phosphorus levels in the pumped water during and after the transfer process - and avoid the laborious process of treating the entire upper pond with aluminum sulfate after the transfer.
