If the pool is more than 10 years old, it becomes a liability, not an asset; this is due to small cracks and re-texturing; the Appraisers will actually deduct for the pool.
If the pool has a Diving Board, the Insurance companies do not like this. The Appraiser will deduct.
If the pool is a "plain jane" without a Waterfall, Multi-level, Rocks and Landscaping, with trees that drop a lot of leaves, etc, they will take this into consideration.
Pools tend to polarize Buyers; some say Definitely, some say Definitely NOT!
Having said this; if you have a nice newer pools with all the bells and whistles, you could add $10,000 to $40,000 to the Listing Price.
Good luck and May God bless