How do you maintain your pool in the winter?

Hi, I am new here.
I hope my query can be posted here.

So, winter is near and I want to prevent my pool from freezing. Last year, we were not able to identify our garden from the pool.

I researched some methods to take care of the pool during the winter. So, this is my query, What is a flotation device which was suggested on this blog? http://www.ferraripools.com/blog/pool-for-winter/how-to-prepare-your-pool-for-winter/ Does it help in preventing the formation of ice sheets? Should I spend on it?

Need your advice.