If you do it that way you have to keep in mind that it drains properly when rain, frost or snow lands on it otherwise it may become so overloaded that it will be damaged.
Water them, do not use pesticides, and cover them in the frost of the winter.
Any polymer-based car cover will not let in any water and is great for winter use.
If the water balance is correct then no it will be fine, but in my experience it's generally not so I'd advise to remove it, dry and fold, and store out of direct sunlight.
Flaps that cover the nose and ears under water
Cover it with plenty of mulch and if necessary during a freeze water the ground throughly and cover with a blanket.
by drinkin water
The water is going to evaporate at some rate with or without a cover. You need to add water to the pool at least once per week. Evaporation rates without a cover would be close to 1.5" per week in most areas. k
Yes you can, we use to put them between the water and the cover,as long as you drain the water below the skimmer basket.
By not touching it.
by touching water
The common name for this plant is Elephant's Food or Elephant Bush. If it is still alive after the winter, then feed it and water it as usual. It may need pruning. Next winter, be sure to water it deeply and cover it on nights where frost is expected.
The silver side should be the one "Touching" the water, this allows the light to pass through the blue and light bounding back up from the bottom to be trapped by the silver.