Will the pool be full of Mosquitoes?
No. The water hosts a diverse ecology, which includes fauna that predates on mosquitoes. Mosquito larvae have nowhere to hide. Dragonfly larvae, Water Boatmen, Diving Beetle larvae eat the submerged mosquito larvae, while Pond Skaters and Whirligig beetles scoot over the water surface to devour emerging mosquito larvae from above. (Interestingly, a study of a bio-diverse, naturally occurring pond on a Caribbean island showed it contained no mosquito larvae.) Also, mosquito larvae prefer still water. Water in a Natural Pool is gently circulated.