from peeing the bed at night no stupied answer like stephanie d or angie
My son is 5, so no I would not let him pull the alarm. I would be afraid that he would think it was OK to pull the alarm any time he felt like it. Sometimes he gets scared when he sees steam from my cooking on the stove. It could turn into a situation of the boy who called wolf. Also, I think that is too much conversation in a emergency situation. This is not the time to say what if, it's a time for action. If you are interested in teaching fire safety then there are better ways to go about it. A visit to the fire station for starters. Lou's Safety Patrol on Disney has some great lessons. Plus books and guides published by the FD or community. Sometimes there are so many resources but they are not advertised. Call the FD and look into some options.
Excavate out the pointy bits or rough material and use a play sand or brick sand bed for your liner. If you have 2 inches or more of play or brick sand, you'll be fine. You WANT a sand bottom. Not a hard concrete or brick one. That's just harder on feet and increases your chances of a nick in the liner. Crusher rock is commonly also called limestone screening. That's absolutely taboo for a vinyl pool. Your liner is at most a 25 mil one. You'll hole it the second someone puts their foot down. The softer and finer bottom you have the longer your liner will last. Harder bottom is NOT good. Drop something capable of reaching the bottom and it impacts it with sufficient forceyou now have a hole. Hard bottom, soft liner..it doesn't take much. Bricks or solid concrete bottom?? Who would do such lunacy? Even an inground vinyl pool with a concrete shell has a top coat of vermiculite/portland/sand mix. That vermic is there as a shock absorber.