Instead of getting rid of the frogs, I think the real problem is the noise they make while to are trying to sleep. I might suggest getting a loud box fan, so this way it will droned out the noise made by the frogs. The cover for you pool could be a pain in the ass to fuck with, as well as fucking up your view of the pool. Other than getting a dog out their thats barking will be about as bad as the frogs, covering the pool, or adding more chemicals too the pool water that would burn your eyes ECT I do not really see any other solutions.