Francine,
First, I'm sorry it took me so long to answer. Been working from daylight till dark and too tired to compute!
I have worked as a maintenance girl for a pool company for close to 4 years and have seen every kind of flower you can imagine right up close and personal with the pools. I'm talking some of them trailing over the pot rim right over into the pool water, and haven't seen one yet that was harmed by the environment. Just, if you use pots, use big ones that will be heavy enough to not blow over into the pool.
Some advice though...
when mixing your chemicals to add to the pool, be very careful not to spill on the plants. What you're mixing in the bucket isn't diluted enough to be harmless. What's already diluted in the however many thousand gallons your pool is won't hurt them. As a general rule, if it will irritate your skin to stick your hand in the mixing bucket, it will most definitely harm your plants. also, when, if you close it for the winter, I've seen people who will throw the old chlorine sticks or tabs from the skimmer down on the ground...this will kill anything it's laying on for about 6 inches in all directions.
on a personal note, I despise having either mulch or brick chips around the pool. mulch will constantly blow into the pool and leaves this dirt behind even when you net it out fairly quickly, and brick chips and some white rock have sharp edges that can grind into the liner and make a hole when you try to net it out...you must be very careful.
otherwise, i love lots of growing things around the pool as long as it doesn't get snakey, and honestly the dirt left by the mulch is easily vacuumed out.
it's also helpful to have a leaf blower on hand...the gas powered kind, (we all know water and electricity don't mix well) and blow the deck a time or 2 a week. this helps more than you know until you do it. be sure to blow away from the pool...and it still takes some practice to keep from blowing a bunch of debris into the pool.

I hope this helps and I haven't come off as trying to be a know-it-all or anything. I've been taking care of a lot of pools though for the past few years, and know what's a pain and what isn't. I hope I've saved you some pain!

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If it's under 20 dollars, he don't need to know!