OK, try this.

Pick a spot, at least 1 foot square. Scrub it with a rag till it no longer chalks and is no longer slimy feeling. Check it 24 hours later. If it's STILL not slimy, and not chalking, then it's VERY likely that you have epoxy paint or acrylic that is chalking, and will continue to do so, till the top layer is worn or brushed off.

Bad news: I have -- one time -- encountered a pool painted with acrylic pool paint (I'm not even sure if that's been sold any more) that chalked TERRIBLY. And, unlike epoxy, it continued to chalk all summer, though it did diminish after the first clean up.