If you kill the algae, FIRST, and then fill slowly, using a bucket or trashcan to avoid circulation, you can probably get the water clear enough.

However, I don't see how you'll be able to avoid stirring up what's on the bottom, when you are in the pool leak testing.

But, you STILL don't want to use floc -- it produces a fluffy bottom mess that has to be VERY carefully vacuumed up. It would be substantially more likely to be 'stirred up' than if the algae will settle on its own.