Jim, we have an inground pool with a pebble like deck. The bees will go to the pool, not a question of a doubt. There will also be alot of bees drowning.
My apiary is some distance from our pool, but until I took measures the spring before last to help the bees to understand that there are easier water sources, they loved this water and we were always rescuing bees. The bees still go to the deck to drink the water that is warmed by the sun that splashes out.
You need to provide an alternate water source to try to train them to go to, instead of the pool. It can really be a huge nuisance, the bees in the pool. I would suggest trying to train them elsewhere, like using the very very very dilute sugar in the water. Especially with the bees being close to the pool. This will deter them immensely.
I have a ditch that runs along the width of part of my property that I dug for drainage. Along the banks of this ditch I let a hose trickle. This really helps with keeping many of the bees getting water from this source instead of the pool and deck. But is not nearly even close to 100% effective. It just helps out ALOT. There are hundreds of bees at any given time sipping this water that drips down the sides of this ditch that is warmed by the sun. The bees like to drink warmed water. Beautiful day in this greatest of our lives. Cindi